The tank vent is a green duck bill part worth a nickel. It doesn't fail.
On the mid-size homeowner units , 210 - 250.......the most common/majority of the time/ often the only fix needed.......is the elbow o-ring.
Once the handle assembly is off, ( 5 - 7) in minutes, the oil assembly is right there. Remove the coarse screw that affixes the white elbow to the body. The small o-ring that seals the elbow, to the tank, fails from both heat, and vibration.
Clean the area thoroughly, replace the little o-ring, gently hand tighten the elbow fastener, until it "seats"
Put some oil back in the cleaned, blown out tank, and let the unit sit overnite........oil leak solved.
Of course, yanking the old oil supply line out of the tank, thur that hole......is a simple tug. Cleaning the shoulder thoroughly, and re-seating a new dry line into the tank......should be apart of the dealer repair. Its an hours job to make the entire repair. Use OEM parts, and pay it forward to the next Guy.
