I have taken apart my Moen Bradburry shower/tub faucet and I am down to the stem/cartridge. I am need to know how to take out the cartridge and why this is happening? The faucet is less than a year old!

Clicking on;http://www.moen.com/consumersupport/installation/moen0133/moen0133.cfm
Will get you to a installation guide for replacing a Moen cartridge. You can get a new cartridge from Moen for free call them at 800-289-6636,
Good luck, Tom