MG T-ABC

After 3 years with my TC rebuild I`ve a problem remembering the spare wheel assembly situation even after reading TCs For Ever. I have basically 3 components, A "keyed" shaft threaded one end and which has a disc attached approximately 1/4 from the keyed end. A Spring and the knock on spinner. Obviously the keyed shaft allows the spinner to screw on and hold the wheel. The keyed shaft I assume fits into the key hole in the opening in the spare wheel support frame. However in my case whilst it goes in it does not seem to want to turn and therefore will/does immediately pull out. Before I dismantle the frame to see why it doesn`t turn am I correct it should? also does the spring go between the shaft plate and the wheel support frame which means spring on shaft insert "key" in opening and turn to lock in place. That seems the logical assemply.

The keyed shaft carries the MG badge and with the 'key' inserted in the spare wheel carrier it doesn't rotate and ensures that the badge remains in the correct orientation, independent of the position of the spinner. These piccies showing the assembled retainer may help to explain.

Thanks "antijam" for taking the time and trouble. So obvious and simple when you see it explained.