I had a someone send me a Junior motor that was not working and I was able to get it back up and running. At first it was running very slow. Turns out the spring that presses the brushes against the commutator, which is exposed, was weak. Fabricating a new spring for the brushes put the motor speed back to where it should be. So if you have a Junior and it seems to run slow, Try this simple test. Look at the brushes and where the spring is, gently pry the brush ends apart to apply more pressure on the brushes to see if that picks up the speed. If so just adjust or replace the spring for better contact. If you are not comfortable swapping it out, send it to me. I also fabricate the retaining pins on these that break very easily if your not careful.