My buddy is basically giving me a 5003 (I think) but is not helping me learn how to use it. Figuring it out on my own. Watched the Gamma videos, and a few others online. Then I was mounting the racquet and loosening one of the side mounts and I heard a screw drop to the floor. I have looked under the machine, all over and have not a clue where this came from. Can someone give me a hand and ID this screw please.