There is a special tool made to remove the pump refill check valve. I had one about 40 years ago. I have a bunch of 28 series NOS military carbs that I bought at auction many years ago. I tried to remove 2 of the check valves from 28 model carbs that pumped beautifully. After I removed them and put them in a 228 series GMC carb, the check valves no longer worked. The tool looked like a tap and threaded itself into the check valve and then you pulled out out with what looked like a miniature slide hammer. The threads on my jerry rigging must be too big and are distorting something. Its been years since I have seen a kit that had the check valve, weight and ball in it. And when a Zenith doesn't have an accelerator pump that works, they run like crap.