[AsahiRaccoon]

Hi! Everyone, greetings. This is my first post though I have been reading the reviews and repair related posts and articles on this site for quite a while already. Anyway, long story short, I recently bought a Pentax MX in pretty rough shape for a very cheap price. It has a sticky mirror problem (occasionally sticky). I first suspected it is due to the deteriorated mirror damping foam but it isn't as I removed all the foam and its residue (I will put flesh one on once I fix the camera) to ensure this is not the cause. I then opened the bottom and observe the clockwork to locate approximately where the mirror return mechanism is. I then use a syringe to "inject" alcohol to the area. This freed up the mirror return mechanism and the camera worked great right after. However, on the next morning I tried it out again and the sticky mirror problem came back. I then repeated the "alcohol injection" and the camera again came back to life.

May I ask does anyone have any experience or input on this? Would the next step be adding a tiny drop of clock oil? If so, exactly where I should do it?

Thanks!

[pschlute]

Welcome to the forums. I have two MX cameras and neither has suffered with this issue. Sticky mirror was always a problem with the LX model rather than MX.

Hopefully someone will be along soon to advise.

[Aaron28]

the alcohol is providing temporary 'lube' n likely helping against the gunk n grime but is evaporating so it sticks again.....if you have something very fine like sewing machine oil or even rosonol (lighter fluid)...use the syringe to apply a drop from it.....oops apply yer clock oil in the same area as you did the alcohol
have done this on several sticky mirror/shutter bodies most recently on an ES.....should do the trick, granted its not a cla but should get ya going!

sorry it's not a video but the reference i used for the ES and applied to the other bodies in a similar manner
https://www.instructables.com/How-to-fix-a-ceased-mirror-on-a-Pentax-ES-Spotmati/

[Not a Number]

Try these videos:

You Tube

You Tube

You Tube

You Tube

The lever issue in the Spotmatic video is fairly common in many of the screwmount and K-mount bodies. In the K-mount bodies it often is just a matter of cleaning and lubricating.

[AsahiRaccoon]

Thanks for the welcome!

---------- Post added 02-01-23 at 09:47 AM ----------

the alcohol is providing temporary 'lube' n likely helping against the gunk n grime but is evaporating so it sticks again.....if you have something very fine like sewing machine oil or even rosonol (lighter fluid)...use the syringe to apply a drop from it.....oops apply yer clock oil in the same area as you did the alcohol
have done this on several sticky mirror/shutter bodies most recently on an ES.....should do the trick, granted its not a cla but should get ya going!

sorry it's not a video but the reference i used for the ES and applied to the other bodies in a similar manner
How to Fix a Ceased/"stuck" Mirror on a Pentax ES Spotmatic : 8 Steps - Instructables

Thanks! That's a very good explanation for the "behaviour". I am asking where I should apply the clock oil because unlike alcohol which will evaporate by itself, oil stays and thus I need to be more precise on the applying area. When I am back home tonight, I will try take a picture of the related clockwork and see if you or others can point me to a more specific point of application.

Thanks again!

---------- Post added 02-01-23 at 09:48 AM ----------

Try these videos:

https://www.youtube.com/watch?v=Ky50og-UoSw
https://www.youtube.com/watch?v=0HSg795F5qY

The lever issue in the Spotmatic video is fairly common in many of the screwmount and K-mount bodies. In the K-mount bodies it often is just a matter of cleaning and lubricating.

Thanks for video! I have already seen the first one before though not the Spotmatic one, will take look.

[MossyRocks]

Here I would hope that @ismaelg would drop by and see this. He is pretty good at restoring old cameras to their former glory.

[AsahiRaccoon]

Thank you once again for everyone's help. I have attached photos of the clockwork of my Pentax MX with sticky mirror problem:

- overall view of all the clockwork visible when the bottom is removed.
- white arrows pointing at the two places that I have injected alcohol to, mirror return mechanism works afterward until alcohol evaporates
- pair of images showing shutter cocked (L) and fired (R)

May I ask where exactly I should apply clock oil to? I guess a tiny drop is good enough?

Thanks!

Attached Images

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[Aaron28]

with syringe i use ....it's usually just enough on the tip of the needle that will come off by dabbing it on whatever part....so it's not even like a drop

sorry i do not know the exact spots to lube.....i usually hit a couple different spots where multiple items move together

[ismaelg]

Hello,

Something you can try is putting a small dab of oil in a small paint brush and "paint" the parts with oil. It has to be very little to the point where it is hard to see. In this case, I'd also put the smallest drop where the alcohol helped and keep it upside down overnight to help it flow inside. Can't stress enough it has to be the smallest amount of oil. It is better to do it multiple times than flooding it and make it worst.

Thanks MossyRocks for tagging me as I missed this thread. I have been very busy at work with no time on the forum recently.

Thanks,
Ismael

[AsahiRaccoon]

with syringe i use ....it's usually just enough on the tip of the needle that will come off by dabbing it on whatever part....so it's not even like a drop

sorry i do not know the exact spots to lube.....i usually hit a couple different spots where multiple items move together

Thanks for getting back to me and also for your suggestions.

---------- Post added 02-02-23 at 10:17 PM ----------

Hello,

Something you can try is putting a small dab of oil in a small paint brush and "paint" the parts with oil. It has to be very little to the point where it is hard to see. In this case, I'd also put the smallest drop where the alcohol helped and keep it upside down overnight to help it flow inside. Can't stress enough it has to be the smallest amount of oil. It is better to do it multiple times than flooding it and make it worst.

Thanks MossyRocks for tagging me as I missed this thread. I have been very busy at work with no time on the forum recently.

Thanks,
Ismael

Thank you! I have never thought of using a small paint brush (I build small scale warships, so I have brushes with tiny tips) to lube parts. And thanks for reminding me the "drop" or "amount" of oil must be SMALL.

[AsahiRaccoon]

UPDATES on my Pentax MX:

Thank you everyone for the help and advices! The oil lubrication seems to be working. Compared to the alcohol which works almost instantly, it seems that the oil takes a long time and many more shutter firing/cocking cycles for the oil to get into the parts in need of it. As of this moment, the mirror would still be stuck up occasionally at 1/60s but not at other faster and slower speeds. Does anyone know why? Is it because it is sync speed and there is some different mechanism behind? I used to have a FED rangefinder that has a 1/30s sync speed that is totally "detached" from the rest of the shutter mechanism.

[kypfer]

"Back in the day" of mechanical typewriters and adding machines we used white spirit to thin machine oil which was then applied as a "wash" as required.
The white spirit evaporated in fairly short order, the result being far less oil in the mechanism than would ever be achieved by applying the oil "neat", but still sufficient to lubricate everything.
I'd imagine than any similar thinning agent could be used if white spirit wasn't available, just be aware of potential adverse reaction to plastic parts.

[Aaron28]

Compared to the alcohol which works almost instantly, it seems that the oil takes a long time and many more shutter firing/cocking cycles for the oil to get into the parts in need of it.

maybe do another round of alcohol then oil.......

[vandergus]

I have an MX open on the bench at the moment. Here are a couple pictures to help diagnose the problem. I have the slow speed mechanism and the tripod socket removed for easier viewing. The red arrow indicates the mechanism that releases the mirror after the shutter has completed the exposure. It's on a lever that interacts with the silver gears on the left (green arrow). The small silver gear is directly attached to the second curtain roller. When the second curtain closes, the lever for the mirror release is pushed by a cam and the mirror returns. The screw indicated by the blue arrow is the pivot of the mirror release lever. This could be a good place to lubricate. The second picture just shows the mirror release coming up through the bottom plate of the camera. The last picture shows the bottom of the mirror box. The purple arrow shows where the mirror release hooks on and pulls this lever free. The yellow arrow is another area that could be a problem but, unfortunately, isn't accessible without disassembly. There is a lot of friction at this interface due the large mirror return spring (on the left) and it takes a bit of force to pull it out. It's understandable how just a little extra friction somewhere in the system could be enough to keep this stuck in place.

Anyway, hope you find a solution!

[Aaron28]

hope you find a solution!

great stuff thanks for sharing!