Faulty valve...

[andyoxon]

Inner tube with a faulty presta valve (removeable core).  V.difficult to get air in.  Do generic replacement valve cores generally seem fine?  Anything I can do to the existing valve core to fix?

[jiberjaber]

I usually just treat them as a consumable item and replace (though mine are tubeless not inner tubes)

I think I bought a pack of 20 off Amazon recently that worked out about 39p each.

[PaulF]

I've used the generic ones without issue

[Feanor]

I tend to remove the cores from any tubes I'm binning, so I have a small bag full of them.

( I ( well, Mrs.F ) seems to go through them at a fair rate due to cack-handed removal of the pump head after inflating, and bending the brass threaded bit to such an extent that it snaps when you straighten it. )

I've found that I have 2 slightly different sizes, the threaded bit which goes into the body is slightly longer on some than others. The wrong 'uns don't seal properly. So I'd say carefully compare the replacement with the original in terms of the thread and position of the o-ring seal.

[andyoxon]

Thanks all.  May pick up some generic to try.