To Maris and Brett -

Thanks for your suggestions. I wasn't sure when to get access to the
back EMF. The load doesn't change very quickly and isn't required to
be compensated for quickly either. Yes, it is a permanent magnet motor.

Both yours and Wagner's suggestion are worth investigating, which I'll
be doing.

As I see it there are pros and cons to either. Wagner's system is almost
instantaneous or pre-emptive and empirical but requires more complex
s/w. Back EMF is a little slower, measures after-the-fact, but the s/w is
simpler.

It's a toss-up, this particular application could be done either way. The
customer is chasing an order for selling 40 of these so there's some
incentive not to be lazy and justifies investigating all avenues. Getting
some results shouldn't take too long. I'm hoping to put up a web page
in the near future and it's the sort of completed generic project I'd like
to put on it.

Jinx