Originally Posted by
gsa103
A friend had an interesting failure with a Lezyne screw chuck. The tube had a replaceable valve, and when he tried to un-screw the pump it removed the valve core instead. The pump part of the Lezyne is very solid, but I'm not a fan of buying an expensive pump just to spend more money on a pump head that doesn't suck.
That's happened to me once or twice. It means the core itself was already loose, so it's better to find out about it this way.