How to remove cap from ingenium 1043B flush valve?

SOURCE: How do you get the top plastic cap off the Kohler Ingenium flush

My Kohler Ingenium has no pins. The white cap is attached to the grey lever which must be lifted up before twisting both one-eighth turn counter-clockwise, and lifting off of fill tube. Turn the water supply back on and flush the tube out (cover with cup first!). Use a thin wire rod about 12" long to gently poke down into fill tube to clear any clogs. Also check where the small flexible fill tube exits from the main fill tube. Reassemble and cross your fingers.

SOURCE: K4608 toilet. Ingenium flush valve. Constant

Yes. If it still leaks after replacing the flapper then you may need to replace the entire flush valve but that is very rare.
Fluid master in my opinion makes the best most reliable replacement flappers or you can go with the OEM parts.