Please let us know how it goes.
Connecting a DC voltmeter and pushing the cart does generate a few volts (2-3 volts). I don't have a want to connect a charger to the motor and check it out - but based on this you feel it might be the battery pack? The charger claims fully charged when I plug it in to charge the batts, it turns green and batteries measure 25V.
thanks for the help
Gary Hall