Can anyone help? I have very little water pressure in my bathtub. I do have pressure everywhere else in the house. I called a Plummer and he agreed that it was probably the cartridge. He asked me to pick up a replacement and he would come out and fix it. Problem is, I don't know what model it is. Can you tell from the picture or do I have to rip it apart? Thanks for any help or advise you can give.