A little followup. On checking the timing, it looked perfect; the cams broke over synchronously and evenly. Nevertheless, after much "fiddling", I settled for 1/2 turn to the lower cable. The tear lessened to about 10mm. I'll continue to ponder on this because I can feel that momentary hesitation since the cams are out of time. Adjusting limb bolts made no difference. Tiller is even. My groups (with fletch) at 18m are acceptable - arrows touch. Thanks again for your insights.