Brushed and vacuumed flu pipe and heat exchanger Replaced oil filter, nozzle, and strainer Checked all electrical connections and safeties Preformed combustion and smoke tests Upon arrival found the hi-vent over the boiler was dripping and appeared to have been leaking for some time. Was able to stop the hi-vent from leaking temporarily but when testing the boiler when the boiler temp was high the Extrol tank started leaking from the diaphragm seam. Had to drain system and replace the hi-vent and the Extrol tank. After replacing both we bled the air out of the system. Started and tested the boiler. The unit is operating properly.