I removed the lowers and all seemed fine. There were two 5mm-ish thick plastic spacer-type discs which came off the bottom of the uppers. I put them back in place (I think one on each leg, rather than two on one leg!), put the required oil in and all seems to be plush and fine apart from the fact that without air, the fork will only move 110mm.
I always buy RockShox and remove the uppers to give everything a good clean every six months and this is the first time I've experienced the problem. Any thoughts on what might be the cause would be much appreciated.
are they air or coil? if you remove the lowers which side is it that prevents movement? have you put too much oil in the motion control unit causing hydro-lockout? If you push down harder does it travel further than 110mm?
does the damper rod compress fully with the legs off? if so the seal head seal has probably gone on the damperside allowing oil into the lowers and causing a hydraulic lock before you reach full travel.
As mentioned above, if the damper rod doesn't get full travel with the lowers off re check the oil level in the damper chamber 😀
Thanks I'll remove the lowers and see which of the two rods is preventing full compression. I have only ever removed the lowers, changed dust seals and put the small amount of oil back into the lowers - I've never done anything more sophisticated with them than that. Can the seal head seal be replaced easily / DIY job? Also where's the damper chamber to check the oil level? Thanks.