Fleck 2510 Tank O-ring (18303) and Slip Ring (19197) - Repair Leaks on Water Softeners & Filter Systems Replacement tank O-ring and slip ring for Fleck 2510 & 2510SXT softener & filter valves Replacement parts for leaks that form where the control valve seals against the tank The O-ring (Fleck part# 18303) can become brittle, nicked or cut and allow leaks The slip ring (Fleck part# 19197) can crack and allow leaks Genuine Fleck parts