Faucet turns on by itself

Learn how to repair, for free, a faucet that turns itself on all by itself. You will learn how to inspect the cartridge and my secret technique for increasing resistance in the handle so solve this problem.

[@stevesall]

Should you have stated to first turn the water of at the supply valve before removing the cartridge? I’m pretty certain if you take a cartridge out under water pressure it’s going to cause a problem.