>Believe it or not, I actually have the X and Y motor assemblies from
>a 7475A plotter.  They were working fine, when I discarded the plotter.
>(the plotter had other problems)  If you really believe your problem
>is in the motor assembly (the motor is mounted onto a PCB) I'd be happy
>to send the servo motors to you.

Thanks for the offer, but I believe I have fixed the problem. It seems to
have been a set of pens that were long past their use by date, and the dried
out ink was gumming up the pen change mechanism, as the protective cap would
not let go of the pen when in the carousel. Also sometimes when plotting the
dry pen created enough extra drag that the motor would go into current limit
causing the error.

I did have visions of motors with the gaps between segments filled with
carbon dust from the brushes, or position encoders with duff LEDs and
sensors - always think the worst when dealing with a product you don't have
manuals for, and parts are likely to be expensive :))

Anyway a clean with isopropyl and a new set of pens seems to have solved the
problem. If you need to clear out your locker though, I reckon you could get
enough on ebay for those to make it worth the effort.

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