Most common stock-fault on Z-mech is broken tooth on supply loading arm gear, although that usually results in a jammed mechanism. Also, the main cam (large gear on top of mech) is common to fail at same instance as loading arm (it cracks/warps underneath). I always change these as a pair.
Does the cylinder drum rotate when you insert cassette? if not check stator unit and ribbon connection to pcb.
Another person stated here recently that a jammed pinch roller not decending caused these symptoms on this mech.
Check for any obstruction to tape path, jammed breaks preventing reel rotation.
Also possible is right side front loading gear slipped out of mechanical alignment.
Cobweb, May 2005