I got the info that follows from a DIY forum (link below). Some of it sounds like basically what I did.
The poster's situation was just like mine: "I have the shut off for the hot water in my shower leaking as if it is turned on."
It's a slow stream, quite a bit more than just dripping.
I did go to the hardware store with the cartridge from behind the knobs. The clerk helped me pick out a set (I wanted the new knobs too). I went home, and installed the new set. The faucet works, but still has the same leak I started with.
Part 2 is what it looks like, what I removed and replaced:
So, I went online and started looking for info. In the step by step description below, what I do not understand is the talk about a "seat" and a "seat wrench." Is there something else I should have removed besides the cartridge?
Any tips for what to try next to fix the leak?
Will I need to get into the plumbing behind the shower wall? I can access it from the closet that backs up to it, but I will have to remove a nailed-down panel.
http://forum.doityourself.com/showthread.php?t=163890Shut water off at main; the first valve in the water line as it passes through the floor or the wall.
Remove the handle on whatever side the temperature of the water is.
Remove the stem. Use faucet wrenches, try not to destroy square edges of stem with a pliers or channel locks.
Pull out stem, go to a local Service plumbing supply house, tell them that you need the faucet seat and seat washer, bibb screw for the stem you have.
Most times, the stem does not need replacement, just the wearable parts.
You will need a seat wrench to remove the seat inside of the faucet; do not leave seat in faucet, it is probably rough edged, which caused the seat washer to disentegrate to begin with.
Use plumber's grease on all threaded areas, and all moving parts of stem when reinstalling.
Make sure that stem is wound out in the open position when reinstalling stem. If this is not done, the stem will only partially screw into faucet housing, thus causing shortened stem travel for opening and closing of valve, and a potential leak inside of the wall that can go unnoticed.
Snug stem back into faucet, reinstall chrome trim for stem along with handle, and test for proper operation.
Make sure that brass bibb screw is tight holding seat washer to stem. Bibb screws can loosen up through operation of stem over time.
edited to add more info I just found:
http://www.stemdoctor.com/2_handle_bathroom_and_kitchen_faucet_repair.htm
Cartridge Type
This is known as a washer less faucet, but as you will soon see, most do use a type of washer. The most common type is made by Delta/Peerless, Valley, and some imported clones. Follow the above instructions, remove the cartridge and inspect the bottom for nicks and scratches. If nicked, it needs to be replaced. If not, look down into the hole that you took the cartridge from and at the bottom, you will see a black rubber piece. Pluck out this rubber seal and remove the spring below it also. Replace with the correct type. They all look about the same, so be sure to take in the cartridge to get the correct match. Most other types of cartridges cannot be rebuilt and must be replaced.
Now, my kit came with a rubber piece and spring, but I did not see anything else in the hole, and didn't feel anything back there either. I could just feel a solid back with a smaller hole in it.
Thanks for any input.
BTW, on an unrelated subject, for any of you who might be curious about how my job of tearing down the cabinets went, I decided to hold off until the end of October. I wanted to make sure I had some money on hand in case it did damage the ceiling so I could afford to fix it if I screwed up. When I get to it, I will update y'all:-)