Brushed and vacuumed flue pipe and heat exchanger Replaced oil filter, nozzle, and strainer Checked all electrical connections and safeties Performed combustion and smoke tests While performing the maintenance we found high levels of sludge at the oil filter. After getting customer authorization we added sludge additive to the oil tank. We also found corrosion starting to form on the inside of the boiler between the sections. Brought the customer down and showed them the corrosion. Recommend replacing the boiler at some point in the future. Upon arrival we found the pressure relief was dripping. Could not see the pressure through the sight glass of the pressure gauge. Removed the plastic and found the boiler was at 30 psi which will cause the pressure relief to drip. Found the autofeed was leaking water by and caused the pressure relief to drip. Drained some pressure from the system and valved off the autofeed. Pressure when leaving was 19