Thanks for the suggestions folks... I came across these guys today.
Since our motor is universal, I'm wondering whether these DC drives might do the job:http://www.kbelectronics.com/data_sheets/kbwd.pdf
(although this one doesn't seem to have reverse)
If the motor is universal and doesn't have a reverse switch built-in, it won't go in
reverse - that's why its universal, ac and dc (either sense) all push it the same
direction. You have to reverse the stator windings w.r.t. the commutator to reverse it.
If you've got a reverse switch, or separate external access to both stator and rotor
connections, then you have a way to reverse it, if there's only 2 wires you cannot.