Not sure about the whirring noise myself. Carriage did move up and down the track carrying its own weight, but would not move with a load (person) on. To a certain extent I would have thought that if it was just the battery then it would not move and also be silent under load, so not sure what the whirring noise in this instance could be (slippage between the motor and the pinion?)
I do not know by what method the motor drives the pinion gear, as the whirring would possible suggest a fault there.
