there are speed controls out there made in china on ebay that i have gotten that work great on perm mag dc motors. they run around $20 or so and can be used to replace burned out units if thats the problem. if you can you might check the motor brushes if easy enough to do for being worn out. any one having these prob’s get back to me i might be able to help. i think the ones i got they make one for 220 too as they are set up to accept ac and dc input power and dc out.
gemmakermz@cs.com