Jeff: I don't see anything recent by you on comp.periphs.printers, so
I'll ask here on sci.electronics.repair:

I have a LaserJet 2200DN that is having trouble with duplex printing:

I followed your procedure that I found online and removed the sticky
goop from the solenoid you highlighted as the main problem, and used a
piece of that thin adhesive-backed felt, but I checked the other two
solenoids and determined that they were not sticking.

The first double-sided document I printed -- a single sheet -- printed
fine, but trying to print multiple copies produced a paper jam, with a
sheet sticking out partway -- on the point of feeding back in to print
the second side -- and a sheet in the duplexer tray.

Subsequent attempts to print even just one double-sided legal sheet
result in a jam: the paper seems to be on the point of feeding back in
to print the second side, but there is a "chattering" sound, and the
paper can be pulled out easily. If I try with a letter-size sheet, no
paper sticks out: the edge is just visible when I open the back -- same
when I do the Engine Test.

Sometimes there is a "ch-ch-ch-ch" sound just after I turn the printer
on -- a sound that I do not recall previously.

Before I "attacked" the solenoid, the machine would jam with the paper
sticking out further from the normal output slot, and with the leading
edge of a page about even with the black roller.

Could some parts of the mechanism have become "unsynchronized" while the
plate with all the gear wheels was removed and when activating the
solenoids enabled springs to turn gear wheels and shafts? -- I did turn
them back to the point where the solenoids were preventing them from
turning by the spring action.

I'd be grateful for any assistance you could provide.

Perce