I just picked up a first gen Cummins, of course the first thing to do is the KDP. As i took the timing cover off and at the very top by the injection pump gear it looks like it has rubbed a little bit. I took a wrench to see if I could tighten the nut on the gear, it moved about a little less than a 1/4 turn. Could the gear be warped or is there another cause?

 

Did you check for endplay? The whole shaft could be walking in and out.

Has the injection pump been changed? Could have been the old pump doing it?