Hi, my redring shower has been pretty reliable for 20 years(i know lol), ive had to replace the heating element in the past, that was because shower was running stone cold,now suddenly im having to turn the shower temperature dial to its highest setting instead of its usual 2 or 3 to get warmth, which reduces water pressure obviously, any thoughts, as i say im used to the heating element packing up completely but not this new phenomenon, thanks in advance