I'm trying to adjust the temperature monitor to make my shower hotter. I have a stubborn 11 year old single lever shower handle made by Pioneer that I'm unable to remove, although I've taken the hex screw out. I've applied WD-40 and a penetrante to lubricate it and also have placed a hot hair drier on it for a long period of time, then I pull but it won't come off. The handle feels loose but also like there is something holding it in place? Is there any help out there?