Laserjet 5MP marks back of page

[wakibu]

I have a Laserjet 5MP that has begun to leave tracks down the *back* of each page. They are regularly spaced marks, as though made by the teeth on a gear, and occur vertically about an inch or so in from each long side of the paper. I think I have even seen four sets of these tracks spaced evenly across the page, but only two show up consistently.

The marks are not consistent - one page they will be obvious, the next not, the one after that obvious again.

Any thoughts? Thanks!

[MichaelTech]

Look at the toner gear. Clean it! also clean the transfer roller, and you might need a new fuser.