Mark,what would cause the PM310 to blow bar oil out the exhaust?
I also found the problem with the choke plate not opening all the way.The carb box that you used in it is the culprit,it prevents the choke plate from opening fully.I'm pretty sure I can use my Dremel tool to sand out on the bottom a bit & that should solve the problem.
If the oil pump is badly worn some bar oil can seep past the piston (in the automatic oil pump) and get into the crankcase. I replaced the o-ring at the base of the pump and didn't notice any problems when I ran it but I did not leave it setting overnight fill with bar oil before I ran it. Usually when the oil pump is worn and allowing a bit of oil to seep back while setting, the saw will clear out in less than a minute when you start it up and run it. The other option would be to replace the automatic oil pump with one having less wear. I can send the pump from the other saw if you'd like to try it, but that saw evidently had more hours as it had less compression.
The airbox and the choke parts were the only parts I received with the saws. The AF bracket and choke plate on your saw are from one of the older saws that do not have the integrated air box/cover and as you can see, don't fit properly in that air box. You can modify the choke plate, the air box, or swap them out for the parts from the later saw.
This is what the AF bracket and choke plate are supposed to look like with the integrated air box/cover.
You can see that even the correct set up does not allow the choke plate to move fully out of the carburetor bore.
Mark