examined DUK Hot Well unit. thermostat stem hard to move and main flame low. found blockage in orifice. main flame good. pilot not holding. need to rework pilot because well pan is deteriorating and falling into burner pushing main flame into thermocouple causing premature wear. Will order parts and return. 12/11/20 replaced thermocouple and thermostat on left side. reworked pilot assemblies to keep thermocuple away from burner. tested. good to go