DC 12 yes its obsolete but customer wan't it fixed dam the torpedos

[COPYDOCAZ]

Poor copy quality went out and the transport belt was shredded due to a broken tension er on the belt so I rebuilt the primary TB unit but the copies are still lite but the image on the belt is good so I replaced the 2ondary transfer unit. no improvement. I am thinking power supply but am not sure the secondary unit is lifting for good transfer. I have tried to get them to upgrade but they are using old computer systems and don't want to upgrade. Any help would be appreciated.
Thanks in advance

[exCSER]

Hi,
There is a sensor on the 2nd BTR that will cause a fault if it doesn't lift. Do you have a PWS?

[COPYDOCAZ]

No on the PWS but I have the manual

[exCSER]

Sooner or later you're going to need a PWS to service the Doc 12