/diy/ - Do It Yourself

I can shut most of it off by tightening, but it reaches a point you have to be a national strongman to get it any further. Tinkering with it also produces black water to drain out for a few seconds when I turn it on

It's been dripping at a rate of one drop every two seconds. The goal was replace the cartridge, but I can't even get the water shut off. Would it really be a cartridge problem or something else?