Sonic Shifter Drivetrain Problem

[juchong]

It sounds like the transmission may not have been assembled correctly. I would take it apart and make sure that it is assembled in the correct order and with the correct gears/spacers/bolts.

[Bill_B]

Out of the box we had one box that spun freely by hand and one that would not. I think they loosened and then re-tightened the plate screws to get the tighter one going. I bet you tried spinning the axle before installing at least one of yours, but maybe you didn't try both. There was also an issue with the plastic spacers for the CIM shaft. They put the pinion too far into the box so it was partly beyond the 1st stage. I overheard the muttering about AM as he used washers instead to space the pinion gear correctly.