Hot water shower valve leaking behind tile when turned on

[Jim808]

Clean out/overflow says Price Pfister. I took apart valve as far as I could, not sure what to do next to get at cartridge. I have additional photos.

 

[GReynolds929]

Can you unscrew the escutcheons counterclockwise?

 

[Jim808]

Plate against wall just spins. turning the handle counter clockwise turns on water

 

[GReynolds929]

What about the piece between the wall plate and where the handle attaches? Might be a good idea to turn water off just in case.

 

[Jim808]

turned water off, tried to turn it both ways, but stopped, worried about breaking something.

 

[Jim808]

brass piece inside looks like it has grooves for a tool to bite. but not sure
Going into town, to see if Ferguson has any ideas. It's at least 35 years old.