Hi Bon,
A good place to find parts is MFG Supply in the States. Rings, carby kits and gasket kits. I have used them regularly and H25/30 parts should be listed ok. Should get all parts less the PTO seal which is a 28540 part number from memory. This can be sourced from a mower shop who has an account with GA Spares as you can't buy directly from them. My carb just had a brass needle and no rubber seal.
Regards,
Mr Jones.
