presurizing the tank usually does nothing if the grit that clogged the oil passages is hard, you will probably have to use carb. cleaner and cleaning brush or wire to unblock?

Does it have manual or automatic oiler? oil exit to chain should be no different. Should have oil slots, holes miled into the bar that aligns with slots holes in the saw side plate between the studs that holds the bar on for adjustments. I would try to google manual for your model see what you got.