ok, i have had a steam/shower cubical you know the ones monsoon,hand shower/back massage/footmasage, steam function, its been fine untill lately the water dose not get any hotter than 40 degrees when the knob is turned to max 55 degrees if you turn it to 30 it is freezing cold, only seems to go to about 40 degrees , dont know much about thermostatic valves, any ideas, cheers