Hi Wayne I have replaced one earlier this year the seat cover is easily replaced by removing the back tool box panel and snipping the cord that runs through the seat (its a tie cord), you then have to careful bend back the retaining lugs that secure the seat as if corroded they will snap off. When replacing pull the cord and tie off and cut the surplus cord…. I actually lost quite a few of the lugs but used some 1/4 inch aluminium right angle to secure the seat to the base drilling through and using self tappers ( I do not notice the seat difference) I bought mine From Ebay but from a Hungarian supplier… I buy a lot from Ost2Rad and would suggest if buying from them you buy several things as that way you maximise against there postage cost (around £14)
ATB
Stuart