How to remove shower cartridge. Help!

[kenny123]

I am trying to get this shower cartridge out without breaking it, but I don't know if I'm suppose to put a wrench on it or what. There are negative and positive symbols on it, with arrows, so I'm assuming I turn it in the negative direction to take it off. The negative arrow points to the clockwise direction though. So do I abnormally turn it clockwise to take it off? I've already turned the water off at the shower, by the local hot and cold shutoff valves. I see the flat surfaces on the metal part and read in another post that this is the place to attach a wrench to turn it. But, it seems to be sticking and I'm afraid to put too much force. Should I just turn harder? Does the plastic looking part come out with the metal part? It said Premier brand on the handle plate. Greatly appreciate any help.

 

[havasu]

Just guessing, I would soak overnight with PB Blaster. The following day, I would shut off the water throughout the entire house. Use a large crescent wrench, size to the large notches. Unthread (righty tighty, lefty loosey), pull cartridge, replace.

 

[kenny123]

I'll see if I can work with that. Appreciate the input

 

[Mr_David]

The black plastic plate inside the wall is a guide shield for tile installation.
Usually removed after tile is set.
Installer maybe did not know how to use a tape measure and drilled the hole in the fiberglass a bit off.
Sometimes installers leave that on to hold the valve against the back of the fiberglass because again they don't know how to use a tape measure and how to set a valve and secure it before they set the enclosure.

 

[kenny123]

Interesting. Hope that doesn't create a problem for replacing what I need to.