Thank you prd,
Good idea.
I did check the cutter shaft for movement when I had everything apart earlier on, and I had the blades off twice on Sunday trying to trouble shoot this mess, and the cutter plate wasn't moving around unusually then.
Looking at pics 1 and 4 of my post above, #90743 on 31/03/18, see how the shaft with a nut and washer on it hangs close to the cutter idler pulleys.
That is the shaft for the clutch drive idler pulleys (which are absent in the photo, because the shop gave me the wrong pulleys.) I had removed and replaced that hanger to have a closer look and see if the raised section came off the shaft, allowing a different size pulley to slide on, it didn't.
On final reassembly, I went from this pic as the template of how everything fitted, not realising I had taken the photo after I had refitted that hanger so that the pulley shaft is more to the rear than the front.
I think this is the problem. Statically, the pulleys had clearance, but with everything running, they have been interfering with each other.
Will photo it when I pull it all out yet again. Im getting good at remove and replace on the clutch assembly....
