jams when duplexing

[ryan.gall@dciinc.org]

I have a 5si with about 110k on it, fuser is about 10-20k pages old. All the sudden when printing double sided I started to get intermittent jams. When It jams two pages will be stopped in the paper path, one page will be in the diverter and the other page right inside the window above the paper tray(I believe it is in the duplexor). If I take the duplexor out then it will not jam or if I print single sided it will not jam..
What could this be?

[ktech]

I have seen this before your duplexor is defective replace the duplexor.