Grohe Grohmix - Water not hot enough

[LPRiver]

I have an old Grohe thermostatic shower valve. After replacing the hot water heater, the water no longer gets above 85 degrees in this shower. Had several plumbers look at it and they all gave up. So, I am attempting DIY adjustment. This is as far as I can get. Any ideas on what to try to increase temp? Cold water is cold. Hot water is Luke warm. Sinks have no issues. Plumber recommendations in the Atlanta area?

 

[Terry]

 

[Sponsor]

 

[LPRiver]

Thanks. There is a screw inside the center casing that I’ve turned left as far as possible. Still won’t release the cartridge. I was able to remove the brass housing. Totally stuck!

 

[Reach4]

Thanks. There is a screw inside the center casing that I’ve turned left as far as possible. Still won’t release the cartridge. I was able to remove the brass housing. Totally stuck!

So you got #9 from the drawing off, and 10 and 10.1 are stuck? I have seen some suggest turning the water on to see if the pressure helps. Maybe have a helper, with a bucket positioned to catch the shooting water and pieces.

 

[CKing]

Is the thermostatic cartridge in the valve Grohe 47111000?

 

[PDIG]

i have same mixer valve and not able to open further see photo. appreciate any help.