A while ago, I had my FED3a (one of 10 FEDs) in pieces to fix a shutter release fault and complete a CLA. I learned a lot doing this. One thing was just how the slow speed escapement was engaged by the shutter speed dial. On mine I had problems with the first of these slow speeds, the 1/15th. As the winder nears the end of its travel when cocking the shutter, the very last part of the movement cocks the little clockwork timer. Any variation in where the winder stops will affect the timing of the speeds. The winder on this and some other such shuttered cameras doesn't always engage on that very last tooth of the winder cog, so doesn't cock the timer to the full 1/15th. Times can be much shorter. It's difficult to imagine a fix for this design feature, so I left it as it was, who needs a 1/15th? Well, I did! While running a group of lens tests, more (..oh, so much more....) about this later. I needed 1/15th at f8 as part of the test. I used my mint FED3b, which, you can guess!!! fired audibly differently on a few shots.
In that moment I both knew what the problem was and that I no longer have the will to persue it. Later, I tried in vain to console myself with a browse of FSU gear up for auction, all to no avail. I must be cured!!!
Have I now reached the bottom of that slope? Maybe a Bessa would help?