Just for my interest though, as a complete amateur, how did you re-seal the rubber bung when you withdrew the needle?

It self-seals, Den - the rubber plug "heals" as the needle is withdrawn. I have not measured the needle diameter, but it is very narrow - and sharp !

On the video I found of re-pressurising an Ohlins rear monoshock, the rubber plug that the needle was pushed through sat under a screwed-in, O-ring sealed steel plug. If RE's supplier (Gabriel IIRC) had provided something similar I suspect that their shocks may hold pressure longer than 2 1/2 years. It may well be that after multiple re-pressurisings the rubber will not seal itself - probably time for a change of units then.

Nigel B.