Hi!

I really think the controller is telling it to shut down
since it is so repeatable. I can watch the voltage shut off when
the head reaches the home position.

If memory serves, these are just a permanent magnet DC motor--not a stepper
type or anything quite that fancy. The positioning is done by way of the
encoder strip. In other words, it could well have built up a short circuit
by way of either conductive whiskers or something that has broken and
changes position just enough to cause trouble. Maybe the components
responsible for driving the motor don't start to break down until they've
been loaded for a while?

When that happens, the controller might just shutdown on overload, instead
of burning up.

I've never had one of the carriage motors quit, but some of mine have had
the spring that holds the belt tightly in place start to back off. When this
happens, the printer may make "twanging" or "gritty" noises like gears
stripping. If it gets bad enough, the controller shuts down and lights
flash.

I would think that taking the motor out, cleaning it well and putting it
back might solve the whole problem. Even today these printers have a lot of
life left in them and the ink can be downright cheap compared to a new unit!

William