[adamvs]

Tormach manual exploded assembly drawing shows this as a 6x26 screw.

So if it's a 6mm cap screw it takes a 5mm allen wrench.

Here's a thought also: REPLACE the chinese black oxide cap screws with real cap screws. The chinese black oxide cap screws *should* be grade 10.9 ( our grade 8 ) or better yet grade 12.9, but most likely they are the equivelent of our grade 5 or worse.