Hi, i think i have stripped the main stem that the handle nut screws into, because the nut wont go all the way down, which makes the handle difficult/squeaky to turn, and has possibly messed up the white plastic piece because i now have a fast drip. Here is a picture of what im talking about: this is the brass stem (or whatever its called) that i think is stripped: and this is how the nut wont go all the way down, which screws up how the plastic piece and handle fits on it: Can i replace that main brass stem piece? Do i have to take the sink out to do that? There is a hex shaped brass part at the bottom of it (you can see it in the first picture)... does the brass stem screw in and out of that, or is that part of the stem itself? Thanks for any help!