Exactly. Most faucet issues I've dealt with come down to the cartridge or valve assembly. Cheap plastic cartridges warp or crack easily, causing leaks...

Totally agree on the vinegar trick—that usually does the job. One other thing I'd add is checking the shower arm connection. Sometimes, if the threads...

Good advice on draining the lines—definitely buys you breathing room. Epoxy putty's saved me a few times too, but you're right, brass fittings are the...