Dell C2660dn Paper Jam - 050-121

The printer has syopped taking paper from Tray 1.  There was actually a paper jam, which after a lot of searching we seem to have removed it all.  But now the paper seems to be picked up and taken in to the printer 3-4 cms but thats as far as it goes.  I have replaced the pickup rollers and i have tried all of the troubleshooting tips plus the steps in SLN287099 "Running CE Mode (Diagnostic Mode) on the C2660dn / C2665dnf / C3760n / C3760dn / C3765dnf Dell Laser Printers, and the paper still doesnt feed through using the diagnostics.  the manual paper feed tray still works fine.

Does anyone have any suggestions as to what can be wrong?  i have never had any problems before.