Using Window Motor with VEX Ball Shifter?

[Monochron]

We are trying to interface a window motor with a typical gearbox but are a little stumped with what to do about the shaft. We took off the retaining clip, washer, and o-ring inside but it looks like the outer white "gear" is fused to the shaft.

Does anyone know how to interface this shaft with the 3 CIM Ball Shifter? The shaft size of the Window is the same as the CIM, but I don't know if there is a keyway in there or anything like that.