It's not an end float problem, I thought it was at first but after a bit of sanding the spur was still locked solid.
Sydewynder is correct, each of the gears, spur, idler and gear diff housing is 0.2mm+ larger in diameter.
I don't think I'll bother with these for my M03. I've never had a problem with the standard items, even in the velodrome mini they work fine. Just thought I'd try them because they were new

Jim, do you check your gears spin freely every time you install a new set in the chassis? or do you just put them in and start driving? even some of the standard gear sets can hit on the chassis slightly causing more noise at first. But the standard gears usually hit because they are too long, not due to diameter.