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Here is the picture of the cartridge that is still in the pipe. The tab on the bottom is broken.

http://www.rightworksnewmedia.com/bathroom/IMG_0306.JPG

Should that part pull out?

Here is...

I'm assuming valley, because that's what the face plate said, and the cartridge does match.

Opening up the wall and replacing the entire valve is more than I would like to spend right now.
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I just wanted to replace bath tub handles so the place was nice for the new renters. A series of impatient moves on my part and I'm now trying to figure out how to replace the cartridge.

The...