I have had 3 machines with the C2152 code, I got 2 going, but down to print pcb for the third. I have replaced the transfer belt retraction mod kit and retraction sensor, transfer belt, CL7( retraction clutch drive assy), M5,and firmware. Transfer belt does not move or start to move but if I turn it manually with M5 motor it will turn. Anyone have anyother ideas?

It ended up being the transfer belt retraction sensor. Real fun job