Try thinning that bar oil out with mixed fuel, about 50:50 with a full tank. Run it awhile at fast idle. Check if you see any improvement. If you do, dump that out and fill it back up again with regular bar oil and you will probably be good to go. Sometimes that thinned mixture will clean out the gunk causing trouble with the flow through the pump and the lines. That worked for me when I ran into the same problem with my Mac 610I am happy to say that I finally had time to get some work in on this saw, and it fired up quickly, was easy to tune, and runs great. I did end up rebuilding the carb that was on it though. Nice poppy idle to it and some awesome torque.
Although I filled up the oil reservoir, it doesn't appear to be oiling much if at all. I'm willing to bet the oil pump was just so dried out it's not even operating anymore. So, that's next.
Clay