[blumoon722]

I got a Spotmatic SP at a thrift shop today.
I've tried hard to unscrew the battery cover, but it wont budge.
I tried alcohol, vinegar, break-free, WD-40, and circuit cleaner.
I took the bottom plate off and tried all of the above from the inside.
I don't see corrosion leaking out anywhere.
Anyone have any suggestions???

[Alex645]

I got a Spotmatic SP at a thrift shop today.
I've tried hard to unscrew the battery cover, but it wont budge.
I tried alcohol, vinegar, break-free, WD-40, and circuit cleaner.
I took the bottom plate off and tried all of the above from the inside.
I don't see corrosion leaking out anywhere.
Anyone have any suggestions???

Worse case scenario is just changing the battery by removing the bottom plate. You sprayed WD-40 on both sides of the plate after removing it and waited a few minutes?

Everyone has their favorite lubricant, and recently I've had a bit more success with PB Blaster. You could also try thermal shock. Put a hot (200 degrees in toaster oven) bottom plate into a freezer. It may cause enough expansion and contraction of the metal to break the bond.

[blumoon722]

I got it. All that stuff must have worked.
Thanks for your reply

[Cee Cee]

parts bonded together by oxidization or corrosion can be very stubborn it may take quite a while for something like WD40 to penetrate, maybe "Penertrine" might be worth a shot. Also I would suggest making a tool to fit the "coin slot" by shaping an appropriate size flat screwdriver blade for an exact fit so as to get a firm grip on it without destroying the edges of the slot, and may be some gentle tapping on the screwdriver.
cheers & good luck with it.

Oh, I see you got it well done!

[TomB_tx]

The original Spotmatic battery cover had two small vent holes toward the ends of the coin slot. These are often plugged solid and hard to see from corrosion, but I've found you can sometimes work the pointed tips of a lens spanner into them and get enough leverage to get the cap off. After heavy corrosion it can be hard to get good battery contact to the cover, and from the cover to the bottom plate through corroded threads.
Sometimes the CRIS H-B battery adapter can restore meter operation, as the adapter is really a replacement cover that holds a watch battery.

[blumoon722]

When I did manage to unscrew the cover I was surprised to see no corrosion.
The Varia V 400 PX battery looked fine and tested at 1.35 volts.
I cleaned the two vent holes in the cover with a very pointy tweezers, and used a q-tip with circuit cleaner to wipe the battery compartment.
The needle in the meter seems to be working, and I see red on the switch when I do the battery check.
The camera works OK on the higher speeds, but the mirror sometimes stays up on the slower speeds. Any suggestions for that?

[ctrout]

Send it in for a CLA to fix the sticky mechanicals.

[Alex645]

The camera works OK on the higher speeds, but the mirror sometimes stays up on the slower speeds. Any suggestions for that?

Definitely not something most DIYer's can fix ourselves. Agree with @ctrout that it needs to be fixed by a pro.

Last summer I saw three manual focus Pentax SLRs in a thrift store for $10 each. I was very tempted to buy them just because of the lenses. But I didn't need those lenses, and testing it there, I knew it would need a CLA and I already have all the 35mm SLRs I need.....so I didn't buy them so someone with the interest in actually fixing and using them had a chance.

So I do have some symptoms of GAS, but after much thought and self-control overcame that urge. I guess you could say I passed GAS.

[blumoon722]

I guess you could say I passed GAS.

Glad I wasn't there