I have a bath/shower mixer tap which on the temperature tap has a red button which you have to push in to get to the higher temperatures. I turned a tap too much and this button popped out. I still have control over temperature (can actually turn tap further and get hotter water than before now) but is this button vital or is it simply a safety feature to stop you going to higher temperatures without realising? Can it be fixed without changing the whole mixer tap?

Cheers for any help!