RP 3105 - Vertical Lines on Masters (Photos)

[PurDuboisPress]

Hello,
I am trying to figure out what's going on with our RP3105. When I scan an image in "line" mode these vertical lines appear on the print, regardless of what drum is in the machine. When I choose the "duo" option the problem disappears. I also had the machine burn a test pattern in service mode and the lines didn't appear then, so I'm guessing it's not the TPH, but rather something having to do with the scanning mechanism?

I cleaned the TPH with a cloth and a slight amount of alcohol but no dice...

Any thoughts on what this could be and how to troubleshoot the problem?

Pic 1
Pic 2

Thanks,
John

[20gaugeO/U]

Dust in the optics, clean the mirrors