I have a 3 valve fixture, the center one being the diverter. After removing the handle and retainer nut I can't get the stem out. Turning it CCW goes to the shower position and stops. I am reluctant to put too much force on this 40 year old stem. I can see the stem seal and the valve body and no other parts. Of course the valve body is buried in the wall. Any suggestions?
Bathless in Baltimore.

Kissler & Co., Inc. (http://www.kissler.com/)
Some diverter stems pull out after the stem is loosened, some unscrew. Which brand do you have? Peek at the handles.

Thanks Doug. It's a Sterling. The local hardware maven suggests I rap on the body to loosen the stem nut. It's recessed too for for heat from the front but I do have access to the back of the fixture through a panel. My only fear is I'm trying to loosen something that is stronger than the stuff it's attached to.

Shower(less)dog

If the wrench or socket is slipping then get a 6 point deep well 1/2" drive socket. Are you trying to remove this with the stem closed? It should be halfway open as you try to remove it.