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03-23-2019, 06:00 PM   #1
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[Pentax MX] Screw specifications for "bottom main gear screw"

I bought a used Film Pentax MX online that works fine, I 've shot 20-30 rolls without problems.
My only problem is that the screw of the winding mechanism at the bottom of the body got lost...
I am talking about this thing:

I don't know how it got unscrewed but it suddenly wasn't there and today the little "cross-shaped" nut behind it almost fell out, making the winding action inoperable...

According to the manual it's the part C265 (and C221-01) that's missing but I have no idea where to find it. The cap is missing as well, it didn't arrive with the camera.

To be honest (since I am not using the auto-winder or whatever this screw is for) I only need a fitting screw and washer that will keep everything in place. I guess I need a short reverse thread screw with a flat head or with a fitting washer.

Does anyone know what type of screw does this is? (Diameter, length, thread type...)

Thanks for any answers.
This forum really is a treasure trove for old pentax enthusiasts!

03-23-2019, 07:39 PM   #2
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Join Date: Jul 2016
Posts: 60
Left hand thread screws can be hard to find. Id recommend buying a damaged MX to source a replacement.

Alternatively, you may be able to determine if another (cheaper) model Pentax camera has the same part and source one of those instead
03-23-2019, 10:48 PM   #3
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Location: Venice, CA
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The listing says it is a left handed screw (reverse threaded) so even if you had the diameter, thread pitch and length of the screw and diameter of the head finding a replacement will be doubly difficult.

As suggested above source the part from a parts body.

You might try The full part number would be 23800-C265. Chance are pretty nil that Ricoh will have the part (USCamera can order parts for RIcoh). So unless USCamera happens to have it in stock you are probably S.O.L.

The parts list of the service manual page 28 does not list any interchangeable parts with other Pentax bodies.
03-24-2019, 11:25 AM   #4
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A good source of old bodies cheap is shopgoodwill, the shipping is often higher than the camera price.


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