You need to adjust the jig. Put a vane into the clamp, put an arrow in the jig and put the clamp onto the arrow NO GLUE. Adjust the top and bottom of the jig side to side until you get the best contact along the entire fletch. If you do multiple sizes of arrows this might have to change from arrow to arrow.

I also have better luck when I don't put the fletch all the way into the clamp. Leave it out just a bit, about 1/16 of an inch or so. This allows the weight of the clamp to even things out a bit as well.

--Bob