It's the rotor band at the base of the rotor that's been water stained as has the port insert but I've been investigating today and it seems the band is heat shrunk onto the end of the rotor as a blank then machined to suit the carbon bearing. It's the band that's stuck and now I know why. There's no way on this earth it's coming off except in a lathe and we'll have to make a new one.
The stained port insert is trouble too because we need a good face to face seal to maintain fuel pressure and the way we're on at present that isn't going to happen. Good news is though that re-grinding the lower face of the rotor where the ports emerge, and the upper face of the port insert is permissable to mend matters but everything must be kept absolutely square and parallel in the machining process because only half a thou' out and you lose pump pressure. The slight increase in endfloat that would result from this fix can be adjusted out via the camplate. Don't have the material spec on the rotor band as yet but I'll get it. As for the carbon face seal on the pump extension we met those on the boost pumps and they were contrary there too. I fixed those by coating them with T-Cut and spinning them slowly for half an hour. Not a recognised repair scheme, I'm sure, but it worked a treat.
Lots of vibro-etched scribbles on the rotor but... you guessed it, nothing beginning LS.
By the way - I've also confirmed today that this is an extremely early fuel system. The CCU is only number 48!
I'm only a plumber from Cannock...
This is not put on as a public entertainment... it's put on to reach a certain goal.