My pfister shower won’t turn off

[John price]

Hi I have an older pfister shower model and when I went to pull on the temp adjustment to turn on the shower it turned on like normal but the nob refuse to push back in I could really use some advice on how to fix this if anybody knows how. It won’t let me add any pictures

 

[Breplum]

Replace the parts would be a generic reply. Parts are available for good old PP

 

[Sponsor]

 

[Jeff H Young]

I cant remember that specificaly but all those old valves are easy to service