Xerox 6120 用户手册

Media matches the printer specifications.
Media is flat, especially on the leading edge.
The printer is on a hard, flat, level surface.
You store media in a dry location away from moisture and humidity.
You remove transparencies from the output tray immediately after printing to 
avoid static buildup.
You always adjust the media guides in Tray 1 after inserting the media (a 
guide that is not properly adjusted can cause poor print quality, paper jams, 
and printer damage).
You load the media printing-side up in the tray (many manufacturers place an 
arrow on the end of the wrapper to indicate the printing side).

Media that is folded, wrinkled, or excessively curled.
Double feeding (remove the media and fan the sheets—they may be sticking 
together). 
Fanning transparencies since this causes static.
Loading more than one type/size/weight of media in a tray at the same time.
Overfilling the trays. 
Allowing the output tray to overfill (the output tray has a 200-sheet capacity—
misfeeding may occur if you allow more than 200 sheets of media to 
accumulate at one time).
Allowing the output tray to fill with more than a few transparencies.