Hi Dave,
As suggested the common parts eg. bearings etc. are available anywhere it's the componentry that's unique to the mower itself that would have to be obtained from a donor machine that is too far gone for restoration.
Supercuts do come up for sale rather often and the prices are quite reasonable once the seller is educated in the correct price point. As far as the transport wheels are concerned, best of luck with those as you are going to have to improvise using something else I'd say.
Cheers,
BB.
