Hello, can someone please tell me what is the name and part# of this shower faucet stem cartridge? It is leaking profusely. The way it should work is that when I pull up on the stem all the water should be diverted to the shower head at the top. However as it is now, only half the water comes up and the rest just spills onto the floor shower stall. If possible please direct me to some photos on the web of what this stem looks like so I can get correct replacement from Home Depot(?). Thanks so much in advance.