Everytime I string, I mount my racquet, trying to follow instructions by YUlittle. I adjust each set of arms to where they are just snug, only using my fingertips to turn the knobs so as not to over tighten. I make sure that none of the brackets are wiggling or too lose. The last few times I've been stringing, I've noticed in the middle of the job that one set of brackets have come so loose that I can wiggle them back and forth. Other times, I'll find that the racquet has become disturbingly tight, much tighter than I initially mounted it. Any idea what is going on here and how to avoid it?