Thanks Norm,
$50 really? I only paid $40 for 2 complete mowers, I might have another look. Not sure if I can get the starter off without damage if I can not undo the bottom screw . I did damage the last one slightly by cutting it off with the angle grinder. Its still usable but not worth $50. I do have a couple of good ones here though.
I'll try my mates impact driver. That's the one you hit with hammer isn't it. Probably should pull off the flywheel and try to get some Inox into the thread from the inside first. I should see if the motor is a goer first by trying what you suggested.
Thanks Jeff