Hello, yes i fixed it, it was the capacitor.
Get drawing from this site.
http://www.saniflo.ca/downloads/installation/Sanishower,Sanipump,Sanivite_TechDataEFR_May07.pdf
Take unit apart, find capacitor inside (item 38 from Drawing) also called a condenser.; order spare from saniflo parts dealer £25 , refit and seal float switch chamber membrane (15) with red hermatite sealant.
It uses a spilt phase induction motor that has no brushes and is therefore very reliable, nothing else can break on it.
However, my Sanivite 3 now pumps for 2 seconds every 30 secs, but I think this due to non return valve flap - maybe I tightened the jubilee clip to much and deformed it.
Richard A, August 2008