Corner pins happen for one of three major reasons. The most common is poor angle to the pocket. You can throw 6 different balls but unless they are giving you very different angles the amount of hook you are getting doesn't matter. Second, people will struggle with corner pins if their ball is not in a good strong roll as it enters the pocket. This can be a problem both ways. I have watched many guys put a ball dead flush but since they are so obsessed with revs their ball has still not entered a roll yet. This causes the ball to deflect as it enters the pocket, which leads to poor carry. A ball entering a roll too early actually leads to poor angle, its not so much that it is rolling. Finally, corner pins can come from being slightly out of place in the pocket. This is actually one of the least common issues but often is the one people try to adjust. The problem here is usually being too light but not light enough to rip the rack.

 

I would start by looking at your equipment and seeing if you have a tendency towards one kind of break point angle. If that is the case try shining something if you tend towards archy stuff or sand something if you tend towards skid flip. if you do have a good varied line up take a look at what your ball is doing as it enters the pins and see if there is something to adjust there. Finally, if you have passed both of those check take a look at where you are hitting the pocket. Usually for a lefty to leave 10s it means you are a little light. I would try making a very slight adjustment with your feet. Maybe about a half board or so? Some people like to back up on the approach by a couple inches, I have never found this very effective since the oil dictates when your ball breaks.

 

If you are still having trouble after going through this I would then seek out a local pro that you trust. These are just some basic observations and sometimes you just need a second set of eyes.