Love my Wonder Winder.. until it broke. This design reuses the winder knob and the retainer from the opposite side.  Now that I look at the original design, I think there may have been a spacer that I lost, so if you have it either reuse it or use the spacer provided between the main winder and the casing on the knob side. It acts as a bushing and keeps things in place.   

The MAIN block should be printed with supports as it has a hole for the shaft for the knob to make it more solid.  It should seat pretty solidly and stay in place with an M4 bolt, or a sheet metal screw like you see in the pic. That's what I used.    Print with 50% infill for solidity.