First post. Sorry if this is not the correct forum. I have a Fluidmaster fill valve in my toilet. It flushes fine after I cleaned the jets and it fills the tank fine. However, after it flushes and fills the tank, the water in the tank very slowly continues to rise over the course of about 3 to 4 hours until it begins to very slowly overflow. Ajusting the screw attached to the tank only adjusts the water level after the flush. I've read a number of places, incl here, that you should adjust the fill valve down. It is my understanding that can be done without removing the fill valve but I cannot get it to move. There is a metal or plastic ring that twists but does not really seem to move the fill valve. The shaft does not seem to turn to move it either. Any suggestions? Thanks