I have a moen single handle shower faucet that leaks. I think the model number is TL2301
Could the cartridge need to be replaced and how is ths done.

Open the links below will show how to replace the cartridge your cartridge number is 1222, Thanks.

John

http://www.moen.com/shared/pdf/TL2393pt.pdf

Installation Help / Animated Tutorial - Installing the Moen 1225 / 1200 Cartridge (http://www.moen.com/consumersupport/installation/moen0133/moen0133.cfm)