RP3105 won't feed master onto drum

[cobiray]

Machine goes to add master to drum and then throws A02-509. Rewind master and then it kicks A02-555. The issue is restricted to the black drum, all 3 other drums work properly. Tried manually placing master on drum and then re running with the same result. I'm assuming it's an issue with the machine locating the a sensor. Just wondering if anyone else has seen this. Machine has almost 6mil on the print counter.

[cobiray]

Figured it out after a lot longer than it should have taken. Previous tech put the incorrect collar on the projection plate, so when the master was loaded onto the drum, the projection plate was actually moving up and hitting the master entrance guide in the machine, catching the master on the edge of the entrance mylar. He owes me a beer.