The problem may be in the bonding between the dip paint and the glue you're using. And using a WB rest will really put a lot of stress on the fletching mount as it goes through the rest. You might have to try switching adhesives to something else, and put a line of glue down the ENTIRE length of the vane, not just a dab in the front and back. That leaves the entire middle section loose and helps "leverage off" your front and back glue dabs.