Neil Preston wrote:
I had a batch of links to LJIII printer repair, but all but one are now
dead. Have you run across this one?

http://www.fixyourownprinter.com/

I have looked at that site since they do have good FAQs as well as
repair kits.

I did some more debugging and found that the motor sometimes has trouble
turning even when removed from the gears. You can feel it vibrate but
the shaft doesn't turn much.

When turned by hand the shaft turns smoothly. The coils measure okay
with an ohmmeter (~4ohm to centre tap, no short between coils, all coils
have same resistance). I also hooked the motor up to my scope and got a
slightly distorted sine wave from each coil when I spun the shaft. All
four coils had the same shape and voltage (using centre taps as ground).
I think the motor itself is good.

I tried putting a scope on the motor terminals and one of them does look
different. Maybe the driver IC is bad, which probably means a new DC
power supply. I need to do a little more debugging on this or start
shopping for another printer.