I don't think this is a case of "drift" caused by a dull blade. After some more careful inspection, based on OneMoreTime's suggestion, it is clear the blade does not travel at a 90 degree angle to the bed - even when there is nothing being cut. When I put a square on the bed (where the stock is placed) and lift the saw head, I can see that the blade runs out about 1/8th of an inch from the edge of the square at about 5-6 inches above the bed. When the blade is all the way down at the base it touches the edge of the square. As I lift it I can clearly see it running out further and further from the square.
Willys, could you do me a favor and check your saw the same way...lay one edge of a carpenter's square across the bed and the other edge parallel with the blade. Then lift the head up about 6-8 inches. I'm assuming your blade will run true right along the edge of the carpenters square. Since I don't see any way possible that I can adjust how the head (blade) travels in relation to the base, I've got to think there is something amiss with how this particular unit was machined or put together. Let me know if you think there is some adjustment on your saw that I could try to make on mine.