Mario is currently out of order. It has developed a strange behavior when it does a return to origin operation. During that operation, the Y axis is jerky and there is an ugly growling noise. It is almost as if the motors are working against themselves or something.
The rotational axis control is disabled as best as I can tell, but I’m a bit suspicious that it may still have something to do with the problem.
I may have to defer to @Christian on this one.