here's a couple of other ones. http://www.hgtv.com/home-improvement/shower-faucet-realignment/index.html http://www.masterplumber.net/moen_tool.htm
So apparently Moen has lifetime warranties on a lot of their plumbing parts including these leaking cartridges. I called Moen's warranty 1-800 number and they sent me a pair of replacement cartridges for free (plus $10 Fedex 2-day shipping which I chose). Using the cartridge nut removal tool finally allowed me to pull out the cartridge as seen below. This is the cold water cartridge removed and I replaced it with the new one. No more cold water leak now! But I can't get the hot water cartridge out for the life of me. I actually broke the cartridge removal tool (made of aluminum) in half trying to pull it out. I followed the same process as the cold cartridge but no luck. Even my brother, who's signficantly stronger than me, tried pulling it out using vise-grips but no go. Any advice on how to remove the hot water cartridge?