My kitchen sink has a Moen faucet/sprayer in one with the single handle pull up. (approx. 8 years old) Water started running out from under the cover. So I bought a new cartridge, a 1220/1225 model. When I installed the new cartridge and reassembled everything, I found that the thing is still leaking. I took off the handle and removed the covers so that only the brass parts were exposed to the faucet. When I pull up on the stem, no leaks. When I screwed the handle on, without any retainer rings or covers, no leaks. When I screw on the retainer ring and operate the faucet with the handle, it leaks. I noticed that the water is coming out the back of the brass fixture. There is a plastic, hex shaped plug with holes in it. The water is coming from there. ALso, no matter whether the faucet is fully assembled or not, it is making a gurgling/slurping sound when I push the stem to the cartridge down. What in the world should I do? I'm about to lose my mind.