5M folds corners

[HibbardSmith]

I have a LaserJet 5M with a duplexer and tray 3. When I print double sided from tray 3, more than half of the output has a corner folded over. Usually there is loose (unfused) toner around the folded area. :confused:

I'm not even sure where to start looking. It seems to not happen if not feeding from tray 3 or not duplexing. Anyone got any ideas of where I can start?

[Brian]

Have you checked the paper? If the paper is damp it can curl up and fold up if it goes through the fuser for the second time if duplexed.