If the notch was made as a brass part with a round peg on the end a simple round hole in the bush could take the peg end on hold the bush from rotating?
Eric
I think Paul (my engineering chap) did suggest something along those lines. It would need pegs to be fabricated and a corresponding hole in the bush for it to locate into, but still doable.
Interestingly I exchanged emails with Mark Wastnidge about this part that he sells from the Betaboyz store, and a) more stock has arrived (it was sold out when I last checked) and b) the replacement part is machined, so obviously his machinist has come up with a way of doing this. I'll buy one, examine it and see if it's worth going ahead with getting a batch done, seeing as the part is actually available.