Included with the new cartridge was a white tool that fits over the end of the stem. This tool can be used to rotate the cartridge back and forth and help break up the deposits that are holding the cartridge in place. Sometimes even this isn’t enough and a special tool is needed. If that’s the case, ask your local Danco retailer for part #86712, our Cartridge Puller. Once you get the old cartridge out, be sure to thoroughly clean the faucet body with a cleaner formulated to remove mineral deposits, so that you don’t damage the new cartridge on the way in.