Hi guys, I have an Aegnas machine with this clamp i looked at it very carefully and notice there is no diamond coat, just plain metal (must be an older model clamp but look identical) it can't seem to grip the string tightly unless i adjust it real good so that it leaves a mark on the string in order for it to hold on good. is this normal for all grippers out there? or should i buy his new 1012? does anyone use his 1012 model? anddo you have marks on the string?