when i string my racquet with Wilson NXT Tour 18 the string gets squased in the stringclamp. the string is actually flattened. I use no more than 27 kg of tension i have a stringmachine with a lever and a automatic clamping system. the clamping system is like two plates of iron and the space between them gets smaller if you pull the string, so it clamps. Is it bad for the string? Does anyone have any tips on how to avoid it.