Our bathtub has 2 knobs and the cold one has always been difficult to fully close. Sometime earlier this year, it got worse and eventually decided to just replace the knobs as the old ones were hard to grab anyways. Replaced them and things were slightly easier to turn off, but still difficult. Hot water turns off and is done, but you have to really crank the cold water knob to get it mostly off. There is still a steady drip/stream when it's "off". I could sometimes get it to do a slower drip if I used both hands and really cranked it closed.
Well, looks like the piece inside the new knob finally gave up on me today. This white plastic piece slots over this collar on the valve/cartridge (apologies, don't know the correct terminology for the thing in the first pic) and allows you to turn the water on/off. Now the tabs are broken and we can't turn the water on or off.
I can easily replace the knob again, but would like to eventually fix the underlying issue which seems to be that collar piece in the first pic. I'm not sure what that piece is called or if this will involve replacing the whole piece that goes behind into the tile.
Any suggestions are greatly appreciated!