The problem is the chain is not sharpened on both sides. I would guess that because I did it one time. I was sharpening chains and I finished one side, while still on the bar and had to leave. I came back and forgot I didn't finish the other side. When I cut with it would go down and to the right. So I assume the chain is not sharpened.

Put on a sharpened one and see if it works.

Jay

Either the teeth are not sharpened at the same angle or one side of the cutter bar is higher than the other. If it is the cutter bar, cut the high side down with a flat file.

+1 on both replies.

To add to the sharpening issues you have to think about it in terms of cutting efficiency. Each tooth should take the same amount of wood on each pass. A number of things could cause differences. As mentioned, one side sharpened, the other not. Another is that your rakers on one side could be higher than the other, or conversely, your cutters could be short on one side. That is one benefit of machine sharpening, once you set them, you can get each cutter to pretty close to the same length. Some machines require less fiddling than others when switching sides for sharpening. Whether hand or machine sharpening, you should check cutter angle and length plus raker height for consistency. Even if they are off, they will should be consistently so that you cut straight.

One other thing to check is that your bar is straight. You'll need a flat reference surface to do that. Warped bars are less common than cutter and rail problems though.

The one experience I had with cutting at a slant was solved by buying a new bar. Apparently the channel around outside of bar had become severly worn allowing chain to move around.
thanks,

I'd just buy a new chain, especially if I have little experience in sharping, even if you pay to have it sharpen you've got half you money in the old chain on a gamble it may work. why gamble? Save the old one for cutting stumps out and practice sharpen on.

If your father in law has a bad wrist like I do, he probably cuts at an angle, and over time the bar and chain and even the sprocket wear to that position. My Stihl repair man teases me about this all the time. I have a log splitter and I cut for firewood so its no big deal
josh