While trying to replace a broken shower knob I stripped the screw that holds the knob in the cartridge. While trying to extract said screw, the head came off. Now I want to remove the cartridge but all the tools to do so rely on the screw hole being empty. I don’t want to try to yank the cartridge out with pliers because it might break and then I'll have a more difficult problem to solve.
How can I remove the headless screw? It’s really stuck and won’t turn with pliers despite using wd-40. The screw shank is too small for a drill bit extractor.
Any tip for removing the cartridge without breaking it given the situation?