C300i series paper lift motor turning all the time

[Gift]

I have the second case with an almost brand new unit turning one of it's paper lift motors for no reason, even if the paper try is open. All involving sensors are working.

At first occurence the cause hasn't been found after a period of trial&error repair attempts (ended with a machine swap after the entire unit was bricked after unsuccessfull ord replacements). Now we are told to replace the base PCB but that's again not something based of some experience with this particular issue so I'd like to ask here if anyone had this problem here, too and perhaps a suggestion for a fix.

[Bix]

Hi, but in which tray does it happen? Do you know the firmware currently installed?

[tsbservice]

If you mean standart machine tray 1 or 2 paper lift trays I would swap entire Paper Size Detection Assy/ Upper(AA2JR72200) between two trays. This Assy contains M12/M13 lift-up motors.
Plastic may have cracks like on old Toshibas.

[blackcat4866]

I think I'd track the wiring harness back to the BaseB. On ground switching devices, a shorted ground wire will run your motor constantly. =^..^=

[Gift]

Thanks for your replies guys,

in the first case the 4th tray was affected and we swapped the entire PC216 (after fiddling around here and there). Funny thing is that all sensors were working fine in test mode.

As for the current case:

I spoke with my technician and it's not really the same symptome but still related to the lift motor:

2nd tray is the issue here. The lift motor does not turn all the time here but it doesn't stop soon enough. So if you put they tray in and the paper stack reaches the upper limit position, the the lift moter drive thingy that reaches into the tray-shaft "pops out" and does a weird sound.