If anyone wants to remove the push-pull valve, here is a video on how it is done. After removal, I'd suggest replacing it with a SharkBite valve and a steel braided supply line. Amazon has a variety of SharkBite valves, and I saw a packaged deal for four valves at $50. It's an easy fix if you like the idea of a DIY project.
removing a push-pull plastic valve from a toilet - Google Search