I just purchased a head ski wing thunderbird made about 1969, 62 in , 50 at 28 inches. I have only had her for about 3 days and she shoots hard, fast, and accurate, as fast as my bob lee takedown of equal weight. I noticed small liear cracks in the phenolic going up and down in the belly side of the riser where your hand grips the riser. Should I be concerned. I love the bow but want to shoot it also. Also, I would appreciate any info or resources on wing history and the thunderbird recurve. Thanks Bhill