I've been string for the better part of a year now, and a little while ago I bought the alpha pioneer dc plus. However, ever since I got it, I've always had a issue with the main arm sliding. There are a few questions about the movement and holding of the racquet frame that I have. When I have to set the main arms, with the knobs on the bottom I notice that if I tighten them by hand and then go about my stringing, when I'm doing tension, the whole arm actually slides slightly. So I tighten using a wrench, and it doesn't move anymore, but it annoys me because it's damaging the knobs and eating the plastic each time. Why is it doing this? The next thing is, I always try to string crosses top to bottom on any frame. However, when I'm doing crosses(I never really notice this while doing mains.) the knobs that help control the 12oclock and 6oclock arms to hold the racquet loosen over time, and I have to keep retightening as I go about stringing. Why do I have to keep retightening them? Another question is also about doing crosses. There are four arms which help hold the racquet in place at the 7-8oclock/10-11oclock and 1-2oclock/4-5oclock positions, and (like it says in the dvd) you're only supposed to get them touching the frame but not tighten them. When I'm doing crosses, since the racquet is becoming loose-ish I notice it starts indenting the frames because the arms are cutting into it. Why is this happening? The racquet is properly mounted but all this happens throughout stringing the racquet. Any help is greatly appreciated! Hopefully I described everything accurately.