After about a 1/2 push on the advance lever on my M4, it appears to be locked up. I cannot advance it any further and the shutter does not fire. Is there some thing I can fix easily on the camera?
An M4 is a rather pricey camera. It isn't a good candidate for ones first tinkering project. Plus there are many shops that still work on and stock parts for this model.
But if you really want to open it you'll need to make or buy a set of flexi-clamps. Most Leicas are assembled very tight so the proper tools is a necessity...unless you want to turn a $700 camera into a $200 baggie of parts.
If the film is out, look at the curtains and see if they are half cocked. That is if the metal bands are in the film frame area. Where the curtains are located will help in diagnosing the problem.