HP 35500 flatbed image sensor not working

No one covers this machine anymore.

Does anyone know, if this is something I can fix in house, or do I need to order a new part. ... and can I replace that myself.

The machine will no longer auto read material width, therefore it does not reverse to put material at same start point every time. I have a big 2-sided job to run tomorrow.

Any Ideas??!?!?!!!?!