Originally Posted by
3alarmer
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the first four I installed all had defective Presta valves. I could overpressure the pump to get air going into them, but there was no way to let air out without removing the valve core. ... the installed tubes I decided to try fixing with new valve cores, bought in a package of 20
This worked fine, and I didn't have to go to all the work of removing the defective tubes and replacing them, so easier
I have spare valve cores (from old tubes). I will remove the core from the tube with sealant inside (the one that I can not deflate or inflate) and replace it with another valve core. You gave me a good idea.