Anyone recognize this shower stem/cartridge? It is is the center diverted one. The water works but I cannot turn on the shower head with this diverter. Unfortunately, I don’t know how to remove it or what brand it is. Any help is greatly appreciated.
You obviously have a hard calcium issue. Try using CLR or vinegar, spraying it liberally until the calcium is removed. That sleeve may just pull out once you remove the calcium or you may need a faucet remover.
It's possible that it's Kohler, find their tech support #and send this picture other thing you can do is bring the picture to a plumbing supply house usually the people at the counter have seen everything