I've found the original brass chuck on the Silca track pump has served me well for almost 40 years. When it starts to move on the valve stem with pressure, that's an indication you need to replace the gasket. They usually last several years for me. The last time I had to replace it, I got the urethane gasket from EVT instead of the official Silca gasket. It has held up well but it has only been a couple years now, so I can't definitively claim that it is better than the original butyl rubber gaskets from Silca. I see that Silca is now offering their own synthetic elastomer gasket which appears to be quite similar to the EVT gasket, and about the same price.