This is a Miller gun furnace in a rental mobile home I have had for 25 years. Typical 65000 BTU setup in good working order which runs fine. The last couple months I started having problems with oil accumulating down in the bottom of the plastic motor housing assembly. It then drips down from where the case halves meet and drips just enough to make it stink. I changed out the nozzle and cleaned it up as done in the past when I found there was carbon accumulation that interfered with the spray pattern. this time however the nozzle looked fine and I did look at the nozzle mount to see if there was any crack or split which might do it, there wasn't any to be seen. The seat area looked good and there is no sign of stripping out. I checked the specs of the electrodes and put them back in and set it. It ran fine for a while then started leaking down again.
Ok, so that's where I am now. Is there an "O" ring or some other place where the burner can weep or seep oil in there that I haven't thought of?