Let me prefix this by saying I am hopeless at any and all forms of DIY and house maintenance. I have a shower room with a Mira shower, it has two handles either side one controlling temperature and the other turning it on and off. The on/off handle has stoppped working, normally you push the button in, turn and hey presto shower comes on when I push the button I cant turn the handle. This is the handle and button The mechanism seems very simple, there is a circular piece of plastic inside the handle which has a sort of serrated edge This serrated edge grips the metal piece insde the handle to turn the water on and off However it doesnt seem to matter where I place the plastic piece on the metal as whenever I put it back together the handle simply wont turn! The plastic wont seem to sit exactly flush on the metal, I'm guessing the pressure of screwing the handle back on helps with this but I must have tried 20+ times now and cant get it to work. Any help/advice appreciated, I'm sure someone who was vaguely practical could fix it in 2 minutes! I'm getting fed up taking baths and want my shower back!