Damaged clutch adjustment collar needed!

[Pat the Jawa]

I'm just starting to strip the engine from my rusty MZ and find that the adjustment collar which is under the rev counter drive cover, is broken. Under the rev counter cover is a circular plate which has tabs that line up with slots in the aforementioned collar. It's one of these slots which has a piece broken off - piece not present so guess the previous owner just binned it. Does anyone have a spare collar that I could purchase? It's such a pity that damage like this should occur as it's so unnecessary. Thanks in advance.