My ks lev has decided to start compressing by about half an inch to an inch when loaded. Anyone know if this needs more air or is a warranty job?

The latter. Jungle/Stif are very good though.

As above, more air won’t fix it.

If it’s out of warranty they are quite straightforward to diy service, no specialist tools needed and fairly comprehensive how-to guides available.

For a basic service… But if it’s sinking down I’d suspect the main pistony whotsit which as far as I know isn’t user servicable.

Or the cable adjustment possibly?