After replacing my tyre I’ve now got the bottom of the valve stem leaking air, I’ve swapped the valve to see if that makes and difference but think the hole in the Stans rim tape maybe a tiny bit too big so not sealing around the rubber base of the valve stem.

So before I order some new tape to re-do the wheel can I

a) either put some duct tape on top of the yellow tape to (bodge) cover the valve hole and start again

b) redo the whole wheel with duct tape

c) order some new stans tape or equivalent

Thanks.

I had this. To get a good seal I cut a small square of inner tube out. Made a tiny hole in it and pushed the valve through. Then when I fitted it to the rim the tube made a better seal around the edge of the hole. Might work for you!

No need for new tape, give it a clean and a cover with a bit of duct tape, little slit and poke the valve through. Or a wee blob of silicon round it.
Mine often leaks a little after tyre changes but shaking a bit of sealant up over the valve stops it, it doesn’t take much.

I found a small hole elsewhere on the rim tape, I’ve tried patching it up but still leaking so before I loose my temper any more I’ll order some tape up.

Thanks for the tips!

Wee bit of quality electric tape for a patch (you can use electric tape instead of stans yellow tape in fact, it might be less good in ways I’ve never noticed but as far as I can tell it works exactly as well)

I’ve patched with duct tape several times successfully

A bit more duct tape patching seems to have worked, although using a CO2 inflator turned the sealant to some sort of strange consistency.

C02 and Stans sealant don’t play well together.

Re: the leaky valve, when you cut the X in the yellow tape, did you just push the valve through, if so, this will leak. You need to get a needle file (or a threaded bolt) and saw it back and forth through the hole to cut off the four tabs of yellow tape. The end result is a nice round hole with no overlapping tape.