Got a pair of MPC 3003 machines that are putting yellow blotch marks across the middle of the paper. This is a mix of developer and toner. I had this issue on another machine about 6 months ago. I replaced the entire yellow PCDU as there was developer on top of the yellow development unit and the drum was heavily grained. Cleaned up the machine and have not heard from it since. I got these two on back to back days. Same symptoms. Yellow developer on top of the yellow PCDU has the belt drag through it and it winds up on the prints as yellow botches and you can rub developer off the paper. I did the same thing: replaced yellow PCDU's on both machines. Issue is one of the machines immediately did it again with a new unit.

I made sure the top of the developer unit is snapped down into place and made sure I went through and cleaned off the tops of the other PCDU's. I also tried taping the slit where you pull the plastic out of the developer unit when you take it out of the box thinking it may be blowing up there somehow. Didn't help.

Firmware is ok and considering the number of machines I have, I don't think it would have anything to do with this, but it doesn't matter.

Any ideas would be appreciated. Thanks.