Yep, it's keyed correctly. The metal "base" under the wheel is solid, does not move. The screw goes in tight, all the way in. No signs of wear that I can see on the inside of the plastic wheel. Weird.
Well, I tightened the screw even more (afraid to twist any further) and it's a bit better / more straight now. But I can now see clearly that there is play between the head of the silver screw and the top level circular cutout in the wheel.
Normally I wouldn't worry about a detail like this but don't want to loose the wheel altogether