Can any one help as to why my droppy seatpost no longer locks itself out?

I’ve detached the remote cable, cleaned/lubed around the top of the rod but still doesn’t lockout when fully extended or partially compressed.

Only time is does lock is when fully compressed.

I looked at the service instructions but not sure if that would actually fix it?

Cheers in advance.

Mines done similar once, cured by a good squirt of WD40 on the little button under the pivot bit, but might not be the same issue if you’ve already tried cleaning it. Worth a go though.

The seals will be blown, it will need to go back for service/repair.

Probably as Liftman said, but before you send it for service, check the big red crown is fully tightened; also, if you fully compress the post with the red crown loosened and tighten it when the seat is compressed, this gives you less aggressive pop up (i.e., less pressure inside), which might improve things a bit.

Darn!!! Will give it a go this evening and see what happens.