it's not likely the motor failed ... the thing is built like a tank.
can you tell if the motor or something under it like the payout relay is making the noise?
also, can you spin the pinwheel in the hopper a little in either direction, or does it seem to be wedged?
if it won't budge, there's a set screw on top that tensions the top bearing the pinwheel rim rides on. the pinwheel should be snugly held by the three bearings it rides on, but if the set screw is overtensioned, too much pressure is on the bearings and the pinwheel can bind.