I had an issue with a couple of the wheels being wobbly when screwed in place. I checked they were seated properly. It appears to me that the screws are a little bit long and reach the end of travel without securing the wheel.

I read another post where someone has re-threaded these and used thicker screws but I didn't fancy this. I 3D printed some 1.5mm thick washers (1 for each wheel) and this has done the trick.

If anyone would like any, free of charge, please pm me and I'll provide my address. You'll need to send a stamped, self addressed envelope and I'll send five washers in return (PLA with 100% infill for anyone who wants the techy stuff).

Alec.