When mine failed about 2 years ago it worked with some kind of pulsations at speed 2, but could seem to run normally at speed 3 or 4. That repeated over 1 month not more than two before it stopped working dead.

Commutators and brushes were totally worn while bushings were in very good condition. That is because motor was taken out and had been lubricated 15 years ago. The failed motor was original in my 1982 with 240k miles (390k km and no air conditioning).

To me if your car has this kind of mileage it is better to replace the motor.

If it were mine I would look at the possibility to lubricate the new motor. As long as it is not sealed extensively. I took this habit since I saw how much lubricant manufacturers put in bicycle wheel and pedal bearings.

With cleanflametrap.com you are on the right track.