Trouble sealing valve stem on tubeless tyres
First up, readily admit that this is a guerrilla setup. No-name rims, gorilla tape. Tyres are decent Schwalbe tubeless ones.
I've run these rims and the gorilla tape option previously, but had to swap to tubes a few months ago when the tyres I owned got wrecked and would no longer seal.
I've come back to fresh tyres but now I'm constantly getting leaks via the valve. I've tried putting a rubber seal inside to help the seal, but still getting the issue. New tape also applied, and I made sure that the hole the valve pushes through is as small and tight as it can be, but still getting leaks. Nothing coming out of the spoke holes (tested under water) so my assumption is that the tape is sealing fine.
I suppose it could be that the old valves I'm using have hardened the plastic so they still aren't sealing well. Any other things I should be looking at before I drop £15 on new valves?