These guys have given you some great advice, I just want to suggest one other thing that might help. I too use bare shaft testing, the difference for me is that even if a clean shaft gives you good launch and flight it will not show you additional contact from the quills on the base of the shaft. I always fletch a couple of arrows just the way the shooters will be. I then take a razor blade or knife and cut the feather off taking care not to cut the quill off. Then shoot the bare shaft with the cock quill in the position you wish to shoot it. I like the twelve o'clock position for my cock feather, however I have been forced to rotate on some bows to a different position. Wear on the quill will be apparent on the rest material. I suggest building up the shelf on that particular bow, maybe a piece of leather to give it a more radiused function. a little foot power on the rest area will give you the right idea. Seek the least amount of contact, good flight, and good hunting.....