On Tue, 24 Nov 2009 18:05:41 -0800, Jon Anderson wrote:

But... I've been told several times that AC brush motors run fine on 50hz,
just a bit slower.

If it has brushes, the frequency of the supply is irrelevant - they'll
even run on DC!

(If it's shunt-wound, then all bets are off.)

Hope This Helps!
Rich