X2 on Daniel's advice. The good thing about replacing the motor (or even having it reworked) is you will know you can count on it for years to come. The motor on my 68 heater/ac still blows strong, but I had it cleaned up by a friend who does auto elctrical work when I first got the car. Original heat/ac that will burn you out in the winter and you can "cool meat" in the summer.
Ask around at some local shops, I'll bet you can find someone who reworks electric motors in your area, if that's the route you take.