Is a sticking mirror latch lever a likely cause of a winding issue on a Pentax ME Super? What else could it be?

I’ve recently added a Pentax ME Super to my (ever growing) SLR collection.

This one appears to have had minimal use, but it has an issue with the advance lever which I think I know the cause of, but as I’ve never owned a Pentax before, I would like to get some opinions on whether I’m on the mark with this one.

The camera was bought from a charity shop, and has some marking on the body which looks as though it’s been carried around a lot, although internally the pressure plate and winding mechanism looks pristine, so I suspect it’s had light use only.

When I initially received the camera, the mirror was stuck in the up position, which was caused by a degraded mirror damper – it was essentially a thick paste.

I gently pushed on the edge of the mirror, and it flipped down with no resistance from the mechanism. I’ve since replaced the damper and the light seals, and they all seem to be fine.

When I first cranked the advance lever, there was no resistance or sound from the mechanism, and the lever would advance and return to the initial position without cocking the shutter.

After about 20 to 30 actuations of the lever, the mechanism started to operate, and I was able to fire the shutter, although it would take between 5 and 15 operations of the lever to cock the shutter.

I continued gently operating the mechanism, until after some 30 minutes, the shutter would cock and fire every time, however it doesn’t feel as though there is a great deal of resistance from the spring when winding. When I compare it to my Yashica or Fujica bodies, it’s a lot smoother.

I had initially believed that the camera was suffering from the stuck mirror latch lever issue as outlined in the video by Fix Old Cameras found here – https://www.youtube.com/watch?v=NJUeXlA2qjM

Currently, the camera is somewhat functional, however the issue has not entirely been resolved.

In its current state, I have the issue that if I leave the camera overnight with the shutter uncocked, when I come to operate the lever the following day the first actuation of the crank does nothing. I cannot fire the shutter at that time, although I do feel some resistance from the spring when I operate the lever.

Actuating the lever the second time does cock the shutter, and I can then consistently operate the winding mechanism and fire the shutter first time with each crank after that time.

I have tested this every day for the past 2 weeks, and it does seem to be a repeatable issue.

The fix outlined in the video is to apply a small amount of lubricant to the bearing on which the mirror latch lever hangs.

My queries relating to this are:

1. Do the symptoms I have described above sound consistent with a sticking mirror latch lever, or might they be symptomatic of a different problem?
2. Are there any other common issues which might cause this problem, bearing in mind that the camera might have been stored for a long time with the mirror stuck in the up position due to the degraded damper?
3. Has anybody else had a similar issue with an ME Super, and how successful were your attempts at resolving the problem?

Apologies for the length of the post – I’ve tried to be a thorough as I can in describing the issue, but if I have missed anything that is useful in making a diagnosis, I would be happy to provide details.

I’m really keen to get this camera working properly, and I could likely use it as it is but I don’t want to end up with a dropped frame every time I take it out from having to cock the shutter twice on the first shot of the day.

It was an incredibly cheap purchase. £35 for the body, a stunning f1.7 50mm, an equally stunning f2.8 28mm, and possibly the only 80-200mm that I actually like (other than the battered Sigma I have for a Nikon).

Any help that anybody can offer would be very gratefully received.