I would take the two screws that hold the back panel out toward the bottom of the back, remove the back panel, and up toward the top of the back opening you should see the belt going side to side.
Try moving the belt side to side. One thing that can happen with these is the pump can seize and that just freezes everything. That belt should move relatively freely at all times.
Also, does it have a sudsaver?
close up pics of the inside and the under side areas would be great.