Yeah clearance is really tight but you can get the wheels to sit flush, but you can't really get it to roll freely without the collar piece touch the surface it's on. I find that the trick is to push the shoulder connector pieces that have the wheels on as close as possible to the center piece, and of course peg the collar piece all the way in.
And the spoiler wings are supposed to tilt upwards I believe (at least on mine they are symmetrical).
Thanks for that. Did not know this. Have heard of Miyaki because of the C joint but no known design credit up until this point? Great job for a Masterpiece rookie I'd say.