Mark,
I am surprised you can not adapt it for a back plate and bearing. I would think that nearly all 20kVA sets are wound as 3 phase and you are able to take off the 3 separate phases, each a little under 7kVA.
Is it 20kW or kVA? 20 kVA would only be about 16 KW resistive if it is the usual power factor of 0.8 inductive. Newage are based in Stamford, where I live, and are renowned for their robust sets. Retired design engineer lives just opposite side of the road to me. Nearly all spares are available but are probably pricey (but the right part for the job).
Regards, RAB