I had one recently. This is what I did-
New batt, not running. Used Voltmeter on the points that attach to stepper-motor. Look for first a neg then a pos reading--every second. An Analogue meter is preferred to see the pointer swing, but a fast operating (Not Autoranging, as they are just too damned slow!) digital will do.
In my case, the pulses were present and the motor was O/C. New ones can be had from Sweden, but at a stupid cost...
Its part-number is-- 1342 9400, motor.