Is that it I see in the picture with the shutter stuck halfway? When the shutter stuck like that on my M4-P, there was a tiny piece of torn film stuck in the rail. I blew it out and then pushed down the R lever, and carefully returned the shutter to a closed position. A technician at Tempe Camera Repair told me to do that!
Once I did that, the shutter cocked and the film advanced. It has never gotten stuck since. I am very careful not to let the film snag on anything while loading the camera.
now send it to me along with fifty bucks and I'll take it off your hands!