It usually feels hot. What is the typical repair? Are you just re-lubing the gearbox or re-winding the motor?
It could be a dirty commutator on the motor, when you pull the cover off (after pulling the entire unit off the window) there will be 2 small blocks (brushes) that are connected by copper braided wires, make sure they don't pop off, most electric motors just need the brushes cleaned and the commutator cleaned, check the bearings and re-lube.
The gear box will have a larger gear that is driven by the worm gear from the motor, and there is a crank rod that cranks the wiper shaft, make sure the crank rod is not binding on the cover and that everything works when the motor is not attached.
When I rebuilt my Dad's wiper, the crank was binding due to 1 too many shims under it, and it was still new from the factory.