BW Controls 6013-W2 Series 6013, W/Shield (Wire Sold Separately), Stainless E-1P, Wire Suspension ELECTRODES

If you notice chattering and buzzing noises from your liquid level controller, chances are your electrodes have failed; their wires have detached from their suspension points, the electrodes got too much gunk/minerals on them, or the exposed bit of wire that bonds with them have rusted away. These BW electrodes are designed to protect the wire/probe connection from exposure to moisture, through a combination of a sealed wire crimp and a compressed rubber sleeve. If you're in a pinch, you can rig up a temporary electrode by stripping the very end of the suspension wire and bonding it to, say, a heavy stainless steel bolt. It might last two or three years. Do make sure to cut the power off before messing with the electrodes or servicing the tank/cistern that hosts them as they carry hundreds of volts between them when energized.