watched your video
That's sounds like a broken gear in the gear box that driving the arm,
Normal operation, When retracting the controller turns off the Motor when the motor current load goes up because the step is retracted and cannot move further,
But the broken gear in the output shaft is not engaging the gear on the motor shaft, , the motor keeps spinning,
The motor gear slapping against the broken teeth of the output gear
I can explain it to you.
But I Can Not understand it for you !
....
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1997 F53 Bounder 36s