So I've come across a problem on a7750 chronograph movement in that it doesn't self wind.   On close inspection of it and comparing it to another a7750 movement I have it seems that the ratchet wheel driving wheel is the problems as shown in the red box in this diagram     All of the auto winding gears seem to be functioning correctly and the teeth on the larger part of the ratchet wheel gear are all present, but it's not turning the larger silver gear with the 4 holes next to it. Anyway this leads me to believe that the smaller pinion gear that is part of the ratchet wheel must either be loose (I think they are pressed together) or broken.   Now I've done a small amount of work on watches since discovering reps. Such as dial and hand swaps, date wheel resetting and swaps, and I'm not to bad when using my hands, so I think I'm about ready to give this problem ago.   I've read a few online guides and discovered this very handy flash guide at disassembling a eta 7750 movement http://www.eta.ch/swisslab/7750/7750   So to anyone with experience with the a7750 movement is there any tricks or things that you think may come in handy to me?   Thanks!