C4050i Jam from Tray 2

[i-have-fax-problems]

I have a C4050i which jams from tray 2. The pickup rollers nearly don't rotate. I tested it with test program 29 under State confirmation.
The Motor of tray 2 only rotates with interruptions. I've replaced the whole tray 2. Same error. So error must come from the device.
Unfortunately the device works now again on it's original tray.
Has anyone seen this?

[and]

From the firmware version G00-RB you have a fix of "81. J12-01 may occur when PF-P20 is installed. [INC000000063539/PBM-00010856, INC000000064433/PBM-00011263]"