While you have the pump exposed, try giving it a kerosene bath around the spring area and blowing it out. Maybe there is some crud in there that can get removed. Are you seeing any oil coming out around the base of the saw, leaving some when you set it down? The oil hose may have just come off it's connection that leads to the oil exit at the bar hole. The oil would still be pumping, but not to where you want it and dripping out through the bottom of the saw. You have to take it apart to get to that too. That seems like a real possibility if the gear is good and the pump shaft moves. You also have the hose from the oil tank to the pump. With the bar removed, no oil is coming out at all?
According to my readings, you aren't supposed to be able to mod those saws, but I opened the exhaust port a bit and found some slight gains. Be careful not to leave yourself an open port situation if you get to enlarging it. I'm not sure it is worth it, might make for less mix in the combustion chamber and harder starting. Mine has that a bit now, if not a carb thing.
I can get your parts scan up, hopefully tomorrow.