Since (before) I moved in, the shower faucets and the handle you turn to switch between tub and shower have leaked when the water is on. I spent today fixing this. Thanks to YouTube and the super helpful guys at my hardware store, who actually let me borrow their tools and talked me through the entire thing, I figured out removing the handles, the decorative pipe and the stem valve thing. I replaced the worn washers and put everything back (the valve seat needs replacing, but that's a task for next weekend as the hardware store was closed when I reached that point).
I also figured out how to turn off the water to my bathroom, and bought some handles so I don't have to use a vice grip to do so next time.
The bad part is that it took the entire day and the hardest part was the physical strength needed to unscrew things that have been in place for 30 years.
My neighbor upstairs had the same issue. He did one himself, then called a plumber as it was too much work to do the other two. He said the plumber charged him $400. I spent $30 and a Sunday.
The best part about this is that I now know how the whole thing works so when I get around to doing my renovation, this is something I can do myself.
Yay me!
