Unsure how to take off Pressure Shower Cartridge? Stuck after handle.

[Fayded]

Hi All,

Trying to update my shower cartridge here, I was able to remove the handle and the screw in the middle of the cartridge, unable to proceed because of the top of cartridge does not move, this is an older shower - I don't see any other screws here, have read similar posts that said CLR or Vinegar, its pretty locked in here, unable proceed. Any advice would be appreciated, thanks in advance. Also if you identify the type of cartridge that might help me in my search, I think it might be Pfister, unsure.

 

[Breplum]

That adapter pulls off. Might use a faucet handle puller of good quality.

 

[Sponsor]

 

[GReynolds929]

Like breplum said adapter pulls off. Valve takes a Moen Posi-Temp cartridge.