I have the same camera that had the same problem, shutter/film advance locked up, and mirror locked up also. Since a coworker gave me the camera for free I felt there was no point on paying $50 or $100 for a CLA, right? So I researched for days online and found 3 potential basic problems for this camera. From problem A the easiest solution to problem C the most complicated. It turned out that by placing a butter knife into the curtain and helping it to wind in the same direction the curtain moves the whole thing was supposed to go back to normal. I did that and it worked, then it got jammed again in a different day and I tried one more time push the curtain with a finger and place a knife to reach one end of curtain and release curtain helping it to wind in position. Camera works fine (cross my fingers)