Some further updates regarding my troubleshooting:
I added fresh batteries into the MCU. Upon reading the manuals, one
of the things that you can apparently do to test the unit is put the
unit into Service mode, and hit the scan button to move the carriage.
I placed the unit in Service mode, and the red LED does not light up.
Thinking maybe there is something wrong with the LED, I pressed the
scan button regardless. There was no further activity by the carriage
or anything else upon pressing the SCAN button.
Tony Miller had advised the prior owner that to troubleshoot the LED
issue, to do the following:
"not having the LED come on when you go into service mode would
indicate that the +12 VDC supply on the PCC interface board is not
working. The regulator on this board also provides the power supply
to the logic on this board and +12 VDC to the mechanism. You should
check to verify this regulator works. In addition, you should check
VRAW to the MCU on PCC J3107 pin 7. It should be about +21 VDC."
I would like to be able to perform the above check, and I have a
multimeter, but I need this translated in a little bit more menial
terms. First, I need to know what to set the multimeter to (DC I
assume, but which setting?). Then, if someone can tell me where to
touch the contact points to from the multimeter on the regulator on
the PCC without lighting myself up, I'll be glad to check it and
provide an update.
Thanks,
VG