It looks like instant gasket to me for the outside seal, to be fair they have never had a problem just the inner has failed so I expect it should be ok! Frank Wrathall himself was supposed to of done the tuning so maybe he beleived it would be OK and maybe there was not enough meat in there to machine the outer ring?

I think I will build it back with a fresh seal and see how it goes, at least I have finally found out after all these years that it does have o-rings...it was something I really did not know for sure...and no det rings in there. How about some liquid metal to build it up? Is that like JB weld? Just something the other side of the seal for support would be good.

Tom:- I might pop by and give those spare seals of yours a go if its OK?

Cheers