If you take the bar and bar plates off does oil come out of the port when running? If so, you know it's oiling, it's just not getting to the bar. Then you'd have to check the alignment of the holes on the plates to ensure the oil can actually get to the bar.
On my old McCulloch there is a check ball there with a spring and it was seized up from lots of crud getting in there. Not sure how your saw is set up though.
This is a good idea. You can trace the shape of the bar and the oiler holes onto some paper than fit that to the saw to check alignment. I recently did this to my MS 460 and found some misalignment. I decided to open up the holes on the bar to 5mm (I had nothing to lose as the bar nose was being destroyed anyway by lack of oil). This made a huge improvement to the amount of oil reaching the bar nose.