DIAGNOSIS The rotisserie motor is overloaded or jammed. The spit forks are not locked into the rotisserie basket properly, causing misalignment.
FIX Remove the basket. Ensure the two spit forks are fully inserted into the basket and the tabs are locked into the slots. The square end of the spit must seat fully into the motor drive socket at the back of the oven. The assembly should turn freely by hand before you start the motor.
IF THAT DIDN'T WORK The plastic drive gear inside the motor housing has stripped. This requires disassembly to confirm. The entire rotisserie motor assembly needs replacement.
HEADS UP Always balance the load on the spit. A heavy weight on one side creates excessive torque and will strip the gear or burn out the motor.