Pressure regulator stuck - Kohler shower

[johncd]

I am attempting to replace an old Kohler, single handle shower pressure cartridge and mixing cap.

You can see the parts here: https://www.amazon.com/gp/product/B001GZU9FY/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Unfortunately, when I took the cap off... and exposed the pressure regulating cartridge, I cannot budge the cartridge. I'm afraid if I clamp down a vice grip and start yanking on the thing I'll damage the copper shower valve the thing is sitting in. Do I just spray it liberally with CLR and hope it comes loose?

Any other advice before I call in an expensive expert?

Thanks in advance!

 

[Dj2]

A lubricant may help. Let it penetrate, then pull, wiggle and curse...it should come out. If you are a little careful, you won't damage the body, and if you accidentally do...replace the body.

 

[Sponsor]

 

[Plumber69]

Did you take the screws out

 

[hj]

IF it is like the one in your photo it pulls out, but if it is the 3/4" model, it rotates a 1/4 turn clockwise to remove it.