My new doughnut arrived today, I added some adjustment to the gearbox support so now I am certain that it is 100% straight.

A lot of people told me to do away with the donut and solid mount it, whilst looking at the old, broken donut I realised that with a little bit of work I could just line up the 3 prongs on the output flange, straight through the same line as the prop, I had to remove a bit of metal and all of the rubber but now it bolts straight through and on to the prop. I have t lost any strength from original and the centre bearing is still in place.

Now I can sell the mint replacement doughnut that I bought (once this has been properly tested)