When you are off the bike, where does the fork settle? Mine settles at around the 10% indicator, which doesn't seem right although TFTuned weren't surprised.

Have you made sure you have a bit more pressure in the positive chamber (top) than Negative (bottom)

1- release all air from negative chamber.
2-release air from positive chamber
3- Re-inflate starting with positive followed by negative, at this point it should fully extend.
4-Negative should have 5-10psi below the positive.

Yep done all that, normally run 10 psi below +ve, TF have recommended that I set the -ve with the bike inverted.

send them back then ?

I think there must be bleed between positive and negative chambers. Can you extend the forks by hand, only for them to creep back, or do they just clunk apart and stay apart?

Can you extend the forks by hand, only for them to creep back

Yes, exactly that, TFT are reluctant to service them until I've made sure of certain things.

Well, if you're absolutely sure positive chamber is at a higher pressure than the negative, then thats all it can be I'm afraid.

I'm pretty sure of that myself, worth doing what TFT said first just in case it saves me £100.

Of course I could send them back to Fisher under warranty but the chances of getting them back in time for the 12 is doubtful.

I suppose I could ride it rigid SS, depends on what my team mates may think. ;o)

You can do it rigid if you like Mike, I'm completely unfussed about pot hunting this year.

FWIW even with 5mm less travel, your SIDs still work a whole load better than my shonk-a-licious Pace's.