Chip on the bottom is sticking out, causing top chips to fall due to balance issues. It's not a big problem with fewer chips, but once you get up to 14 chips, it crushes your shuffle almost every time.
How do you make sure the chips are pushed (interlaced) far enough to where they won't fall with a big stack.
Here is a picture of them; http://imageshack.us/photo/my-images/13 ... 40328.jpg/
Usually the top chips are pushed in further, but the bottom chip (or one or two more) are not pushed far enough in, which causes the chips on top to fall.