Do you have a roll you can use as a tester? If not, put a couple of wraps of masking tape on one end of the spool, on the inner rod up to the edge of the flange. When you look inside the top chamber of the back, you'll see a silver small-geared wheel on the left end. You want that wheel to ride on the masking tape.
Now the camera will act as if there is film in the camera and run the counter. Give it a shot. If the counter does go forward, even if it jams at some point, does the counter reset to 0 when you open the back?
Sometimes it's a matter of exercising the camera. Most likely you are heading to a cleaning and overhaul of the drive system.