Wave drive motors are notorious for problems. I'm not familiar with the the new style neo motors, but the earlier motors were often never cleaned out by the techs, and the brushes were usually not replaced until there was a motor fault code, which by that time it was usually to late and motor damage was done.

That being said, steer throttle fault is a control system problem, not drive system. Do you have the Curtis handset to plug into this machine for diagnostics? If not, you need one, it's very difficult to do good diagnostics on the wave without it. With it you will actually be able to see what's going on with the pots and controller. I'm not sure that you can properly calibrate the pots with out it either.

Just a side thought, have you checked that the front wheels are turning freely?