In theory, replacing a shower faucet cartridge is an easy task. You turn the water off, dissemble the faucet handle to expose the cartridge and then pull the cartridge out. In reality, you will find more often than not that the cartridge is stuck, and despite your best efforts will not budge. Dirt, hard water deposits, or both can cause a cartridge to become stuck inside the valve. When this happens, the best and easiest way to get a stuck plastic or brass sleeve cartridge out of a shower valve is to use a cartridge puller.
Remove a Stuck Plastic Cartridge
Line up the cartridge puller, open side down, with the exposed stem of the stuck cartridge. Push down to seat the cartridge puller.
Turn the knob on the cartridge puller handle clockwise to secure, but do not over tighten.
Rotate the cartridge puller to the left and right while simultaneously pulling up to loosen and remove the stuck cartridge.
Remove a Stuck Brass Sleeve Shower Cartridge
Press the spring pin button on the cartridge puller and slide the puller inside the brass sleeve opening.
Gently rotate the cartridge puller to the left and right until it lines up with the grooves inside the brass sleeve.
Turn the cartridge puller clockwise to loosen the brass sleeve and then pull up to remove the cartridge from the shower valve.