Could be the bearings or (brushes as they are sometimes called) in the motor, not as drastic as you may think, the two brushes go into the side of the motor, they are a piece of carbon block with a spring on the end, sometimes they are screwed in, sometimes they have their own screws at the side, sometime they have a clip arrangement to hold them in, they keep the motor from overheating, remove both of these, one either side, and replace. They could be in a long plastic or bakealite holder, hope this solves the problem, if there is no change after replacing these, remember they take a few revs to bed n, then would replace your orange button, this makes a connection and when depressed applies the brake.Please make sure when you replace brushes that the new ones completely touch the side of the motor then screw back into place with the screws or holder.
John atkinson, July 2010
