Replacement parts for syphonic toilets?

I have repaired my 25 year old syphonic toilet and would like to replace the rubber/plastic parts. Viz. seals within the cistern, the large seal between the cistern and the coupled pan and the thick quarter moon shaped disc which fits onto the suction pipe and prevents water draining into the outlet chamber. Where can these be obtained? It is a pampas coloured close coupled suite/system but has no name printed anywhere on it