If there is any question as to the condition of the motor by all means have it balanced, look at all the parts to see if there are any problems then put it back together and run it. Jetjoe motors are good motors, they need to be tweeked sometimes as the manufacturing tolerances are not as good as other manufactures. I have lots of experiance with jjs as well as other motors. Go slow and enjoy.
Sorry just my three cents.[8D]