We have one at the school, and indeed ended up making some new holders for it. The design is such that overtightening can damage them.
I don't have the dimensions electronically so I'll have to search around. You may also need to make the special spanner wrench but that's much easier.
If I could get one of the machines for a decent price and decent condition, I'd say pick it up if you have the need for it. They're a bit older and not as fast or powerful as the newer machines but saving money with an older one can be nice too.