Burner was off on reset. Reset the control. There was air then the flow stopped. Found the tank valve was plugged. Blew out the tank valve and bled the line. Customer has moisture in the tank. When he changed the filter it was milky and brown. Replaced the strainer and nozzle. Started and bled the line until there was clean oil. Customer is adding an additive to the tank to help with the moisture and sludge. Recommend having the system serviced.