Check the clamp after placing the feather in and make sure it's a tight fit. I've seen some clamps that are slightly open, not much in the center and when the clamp/feather is placed on the shaft, the feather isn't flush.
I never push the feather to the quill, always leave a small amount of feather out of the clamp. Not familiar with the your jig, but after you set it up, make sure the back of the feather sits flush, then slowly adjust the arrow until the remaining feather also sits flush.