Hi Martynn,
Iread your post with interest,because I have the same issues with my ETZ.I have been following this post in the hope that someone would say,”ah yes,it’s this,this or this”Stephen Wades reply is helpful,so I thought I would pass on my theories. Over the two years I have owned this MZ,the clutch drum,friction and driven plates,the lifting mechanism,and the shim have all been replaced with new.It still rattles!I don’t think it’s the clutch at all,but one of the sliding gears.When I pull the clutch in the rattle persists for a couple of seconds untill the clutch plates separate.Its done this for two years and 8000 miles so I dont think it’s a problem.
I replaced my noisy primary gears with used ones that were not as worn,and they still whine,but less so. Most of the parts available now for MZs are aftermarket items and I have found the quality sometimes rather dubious.
Terry Taylor.