I have 2 ir6570s that print great single sided. When they duplex there is a small void on the tail edge. Only about a line of type wide, it moves up and down the sheet. (not uniform). Sometimes it is 2" from the top sometimes in the middle. Always on the trail edge. I have increased trans voltage strung new wire. I think it is happening at paper transfer not drum charge, but I am not sure. Only on letter, not on LR or 14 or 17" paper. Thanks for your help.
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