[radiotechnician]

Here is the Uher 4000 L service manual with the motor circuit scanned.

I serviced Uher 50 years ago, and can tell you motors for the Report, S and L were a continuous concern.
There were three motor types used. The L used the poly phase type.

Perhaps, an ohm meter, analog, could be used on the motor commutator to determine the segment switching contacts are working. That the contacts appear to work while rotating slowly, does not mean the motor can spin up, and start by itself again.

If you open it, you need to be careful. We never fooled with battery recorder motors. But then again we had spares on hand.