Had a tenant do this once - they were moving out of my apartment and their child spilled a blue ink toner cartridge on the carpet. 

First invoice had a description of 1. plumber troubleshoot/inspection 2. plumber had to replace leaking shower cartridge charge was @245.

@Paiea PalomanuReplace the hot water side cartridge now while you’re messing around, it likely hasn’t been done for 15 years and you might as well while you’re there.

Buy a paint respirator with organic vapor cartridges.

The typical configuration for oil finishes is P95 particulate  prefilters fastened over organic vapor cartridges.

Local water hardness has an effect on cartridge life.Ceramic cartridges may last longer.If it's a real tough crowd you're renting too, this might be an option (they might be very used to it).https://www.acorneng.com/security-plumbing-fixturesGood Luck!

HelloA shower knob broke in my rental most likely the cartridge is broken.

Perhaps the most useful attachment for it you'll ever use will be organic vapor cartridges.

Also just a thought to put out there....Does anyone do in-home mailing and if so how much on average does it cost to buy the printer, ink cartridge, and paper material needed to make post cards and also print regular white letters??

I am not a fan of the "Yellow Letter" concept personally, but get yourself a good wireless printer. if you are doing it yourself, ensure you get a high volume one but pay attention to how many prints you can make per toner cartridge.