Anybody help me diagnose problem with Momentum Model T?

[mike killay]

I take it that you have tried disconnecting the brakes. Sometimes the switches inside them can stick.

 

[Birger Bulukin]

Have you checked that the speed indication works normally? If the indication shows above 25km/h when it should be below, the motor will cut out.

One more thing to check before you go to any trouble. Check that the motor connector on the fork is pressed together all the way.