I'm trying to replace my late 90's Kohler bathroom sink faucet valve and I got stuck after I removed the single handle (ball style) handle. I tried like hell to loosen and turn this with channel locks but it wouldn't budge. I started to think maybe it's not something that turns. Can anyone confirm if this is can come loose? If not how do I get to the old valve? This is on a Kohler faucet model # 15191-CP and Valve part number #GP30413. Any help is greatly appreciated. Thank you.