Need help removing shower diverter valve
I have a hot, cold and pull out shower diverter system in my bathroom for the tub/shower. My problem is that when filling only the tub, water squirts out from the center shower diverter stem and some comes out of the shower head itself. I am assuming that the diverter cartridge needs replacing so I tried to disassemble the setup but ran into a problem trying to remove the cartridge. It seems stuck or maybe I am missing some other part, that needs to be removed, before I can take this out and replace it. I cannot see any obvious "c" clips or retaining washers of any kind and have given this unit several hard pulls to remove it to no avail. I cannot seem to identify the manufacturer (maybe Delta or American Standard) although any insight on how to make that determination will be welcomed. Attached are 4 pictures of the valve. The first is after I took all aesthetic materials apart to get to the "meat and potato's" of the valve. The second, third, and fourth pictures are after I have removed an internally threaded nut that I thought was holding the whole setup together. Any insight on where to proceed next will be greatly appreciated as I would like to change out this valve to fix the issue at hand.