Metal tyre valves

[PlayersNo6]

I've got these fitted all round on my MX5 alloys. No idea how long they've been on.

Would you normally replace when getting a tyre changed as you would with a rubber valve?

One tyre has a slow puncture and I cannot see any visible damage so suspect it may be the valve - can they be tightened up?

Thanks

[anonymous-user]

Put some soapy water around the valve and see if the valve stem bubbles up.