Problem solved

Quick recap.....
The last race of 2014 - the extreme bike weekend, we qualified first but after the last round of qualifying i found a problem with the clutch and decided not to run it in eliminations in case it got worse and damaged something.
3 months later and after a lot of head scratching, it seems i have found the problem. At first it seemed the clutch primary gear was bent, I'd measured the runout of the gear by setting it up on an input shaft in a set of cases and using a dial gauge, and by laying it on a flat surface, and it did seem to be simply bent.
Then i decided, to be more accurate i'd put a bit of large diameter bar in the lathe and machine a shoulder into it and butt the gear up against that and bolt it to it, guaranteeing a true surface. This corroborated the theory that it was bent as it had nearly 0.5mm of runout. 
However, in my attempt to mark it up with a view to straightening it i turned the gear around and bolted it down again. Suddenly, the gear isn't bent anymore - no wobble!
I'd never even imagined the thrust surface of the gear wouldn't be straight... after all why wouldn't it? I still don't know. But anyway it was miles off, as you can see in one of the pictures where I've started to cut it flat again.
The surface was tough but with a carbide cutter and light cuts it turned up just great, and i finished it by lapping on a flat plate till it looked consistent.
Total runout now is less than 0.1mm. So i made up some new rivets to hold the basket and gear back together and used a large glamp to hold it all whilst i welded the ends of the rivets to the backing plate.
Sorted.