I have an older Brother MFC-8600 with what seems to be a feed detection issue. Every sheet of paper stops about halfway into the machine, with a perfectly clear half page of toner deposited, but never reaching the fuser roller. The machine claims a jam.Same result with the front feed slot, same result with a self test page. Everything sounds normal, and I've cleaned and dust blasted everything. Is there a way to diagnose? To repair the paper fee sensor?