Hot water problem solved. 2023 tab400

Ghannan

I replaced the thermostatic mixing valve (with red cap) and now I have cold water from cold taps and plenty of constantly hot water from the hot water taps.  Cost =$200.  Ouch, but hot water is behaving itself now.  How can my spare valve be taken apart for inspection/repair fore future use if needed?

MuttonChops

Unscrew top cap:

Ghannan

Is this the one with the red cap?  The top cap must be on really tight!