I had a hard time finding replacement
flapper valves ...... so I made my own. I turned two pieces of
Delrin to the proper diameter, purchased some flat silicon sheeting,
cut out some oversized squares, used a leather punch to put a hole in
the middle, sandwiched the square between the fixture and trimmed it
with a razor. I used Stainless machine screws with Nyloc nuts to
hold them in the cage.