F110 is lack of communication between the scanner PWB and the system PWB. If the scanner board has been replaced, then all that leaves is the system...
You can put a request for the firmware in the Service Manual request forum and someone might offer to give it to you. I'm retired and no longer have...
I think I'd examine, and possibly clean the encoder strip. Ink on the encoder strip can cause this effect. A sticky carriage rail can also cause this...