I have a 4 year old Moen single handle kitchen faucet. It developed a drip. I replaced all of the O rings it still dripped. I ordered the plastic sleeve with brass rings an O-rings. It still leaks. What should I do next?
If you have replaced the entire cartridge, and you have not damaged the seals on the exterior of the cartridge, then the interior surface of faucet would probably have a flaw in it. These seals are called static seals, they seal between the cartridge & the housing itself. You could have damaged the faucet itself when you removed or reinstalled the cartridge.