Mates 454 air pokes. Lost all but 10mm of travel. I suspect a failed o ring on the piston dumping the damping oil.in the lowers. Any other suggestions? Will take em apart and have a look. Where is cheapest to buy the oring and not the full seal kit?

Yeah, what you have said – damping oil now in lower leg.
I’ve had the same thing with my Reba’s before but not to that extent. I think at it’s worst, mine has been down from 115 to ~25mm of travel.

I think LoCo on here mentioned selling just the o-rings you require. Drop him a mail.
Alternatively have a look on ebay, there are people selling DIY seal kits. Obviously bit more risky as you are assuming they’ve got there measurements right.

Sounds like you have it right.

Mine did that once, but it was the seal head (ie white plastic bit at the top of damper rod) cracked rather than the seal itself. …just in case replacing the seal doesn’t do it. Mine was at tft at the time as when damper failed it was due a proper (all seals and valves) service and tft were good enough to install me a ‘recycled’ seal head from a dead fork for free.