Re: Shower faucet
I had nearly the exact same experience you are having trying to remove a Moen shower faucet cartridge. When you pull on the cartridge, you may need to provide an opposite force against the valve body to avoid damaging the tile work -- pulling the valve body against the back side of the wall can crack the tile. In my case, it took a TREMENDOUS amount of force to break the cartridge free.
Do not pry or hammer against the portion of the valve body where the slots for the retainer clip are. You'll bend it out of shape if you do.
I opted to replace the plastic cartridge with a brass one. I have an aversion to plastic faucet parts, but if your water is corrosive a brass cartridge may not be suitable. Make sure that all o-rings or seals on the replacement are well lubricated with faucet grease before installing.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.