What's a "reduced diameter wheel" and where do I get one?
I made mine from a worn wheel like those above. I ground it down against a broken drill bit (which is high carbon hardened steel) to the size I needed to put a small groove in the head of the screw. Careful if the screw is in plastic. Too hot and things start to melt around the screw on the laptop.
It appears they are pretty common on Ebay -
https://www.ebay.com/itm/null-Wheel...ol/372367024108?hash=item56b2cddfec:rk:1:pf:0