Ed, I would just leave the motor in there for the time being. The only thing I would suggest is, since the motor is now 21 years old and you have no idea of how often the previous owner used the vacuum, it would be wise to invest in a armature seating stone and to install a new set of carbon brushes. Once the brushes get too short, the metal holder can get close enough to the armature and cause irreversible damage. This will prevent that, clean up your armature and insure your motor lasts and is reliable for many years to come.
As for how much amps your original motor in this vacuum would have drawn - first of all, know that the next TriStar CXL single speed model used the Ametek 116311 motor which drew 7.5 amps. Both this motor and the 2 speed Ametek motor TriStar used would have both pulled 90" waterlift on their highest speed. So when you say you want to return the vacuum to original specs, don't worry about the amp draw! Amps only tell you how much power the motor uses, it is NOT a direct correlation to how much waterlift and airflow the motor produces or how efficiently therefore it is using that energy. As long as the vacuum is producing 90" waterlift with that motor, just worry about that and be happy if it is.
Now, as to whether you should replace it with a new one and sell your current motor? Don't bother trying to sell yours. Used motors generally don't sell for much. Also, try your vacuum out first with the current motor....depending on the surfaces cleaned daily and the type of dirt you pick up in your home, the current motor may be more than sufficient for your needs. Also, if you use the Kenmore bags I suggested, that will help A LOT, as part of determining whether the motor produces enough suction and airflow for your needs is how well the vacuum maintains it's suction and airflow. If it does that well, you don't need to get a higher powered motor to compensate. So since the Kenmore cloth bags will allow the vacuum to perform better longer, that may be beneficial to you.
I will send you links by email tonight to the 3 motors I mentioned in case you do decide to upgrade. And btw you are more than welcome for the advice I gave above.
Rob
