Yeah it hard to believe it’s the gate valve. Im not to sure myself that’s what’s causing the issue but I don’t know what else. It’s coming Monday and I’m crossing my fingers.I have a 2-year old (ish) Red Sea 750xxl with the original gate valve and thus far it's been stellar. I do have to occasionally adjust it if I find the water level in the overflow drops too much, but this is only something I need to review periodically (ie: every other month or so).