It could be the oil tank vent, which is located between the two bar studs. Clean it up real good and remove the sprocket cover, bar, chain, and inner guide plate and tip it on its side. See if you can physically see where the leak is coming from.
It might also be the oil input hose junction where it meets the pump body. Sometimes those get a wrinkle when the oiler is being installed.
Here is a link to a leak on another saw.......and I have shown in there where my MS660 was leaking bar oil. It explains how to blow some air through the vent to clean out anything that might be stuck in it.