I'm trying to troubleshoot this leaky faucet... these are the valves underneath the sink... [sorry for the upside down pic] every tutorial I look up shows just a hand knob underneath. These can't be turned with pliers because the square protrusion "disappears" into the round cylinder when you turn it... been googling my head off to no avail. HELP plz! Please tell me there is a tool for this, and what its name is. Thanks!