Older printers aren't exactly Linux, except my printers
haven't connected to any other OS since I owned them ...

I have two 20yo HP4050 black-and-white laser printers, and a
slightly newer B&W HP4100 laser printer, recently purchased
surplus for $8 (!!).  The 4050s made noises while they
printed.

The 4100 paper-jammed, presumably why it was $8.  Swapping
trays did not fix the problem; the tray it came with worked 
in the noisy 4050s.  I assumed (wrongly) the problem was in
the guts of the printer.

So I read much of the 4100 service manual, tore it down and
inspected and cleaned it.  It still paperjammed.  At the end
of my patience, I searched the net for service information
... and found a Youtube video about taking apart and
cleaning the INSIDE of a magnetic clutch in the PAPER TRAY.  

The clutch drives a counter-rotating wheel on the tray,
which pushes occasional multifeed pages back into the tray.
Or, if the clutch is jams, prevents paper from feeding.

All three paper trays had quite a load of abrasive black
dust clinging to the magnet inside the clutch, so the 
clutch did not turn very easily. 

The Youtube video guy thought the black dust was wear from
the steel band of the clutch, and he went through a somewhat
laborious but successful process to clean the dust off.

I realized that the black dust is TONER (which is slightly
magnetic).  The best way to keep it from clinging to the
magnet is to "short out" the magnet with a keeper (I used
the nose of steel pliers).  The dust still clings to the
hurky magnet in addition to the pliers, but a LOT less. 
I wiped off the dust with wet Kleenex. 

Like a toner spill, dust can get all over everything, so do
this over a wet paper towel.  Or a regular cloth towel, so
you can ruin the towel and the clothes you wash it with. :-)

Anyway, It took 15 minutes to fix the clutches in three
trays.  Now, the 4100 works great, and the 4050s print much
more quietly.  I will spend longer putting the HP 4100 back
together, then cannibalize something else for 3 more double
start screws to replace the ones missing when I got it.

I write about my older HP printers and trays, but I'd guess
that other printers also use magnetic clutches in their
feed paths, so the above might help the rest of you.

Keith

-- 
Keith Lofstrom          [email protected]
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