My 1800 will not oil. I also have a micro 25 which seems very similar. I have cleaned the oil reservoir and replaced the tube between the oiler and oiler window at the bar. I'm not sure of the theory of operation. How does the oiler work? Does something pressurize the oil reservoir causing the oil to enter the oiler and go up thru the tube to the bar? I saw something on the diagram about a check valve near the clutch; is that relevant?