Hello I have a Chinese CNC 1325 model which uses mach 3. I have already configured everything however there is a moment when I try to write on Granite with appropriate bits, it starts well but the more it progresses in engraving, the worse the engraving does not engrave inside the marble or granite while the machine continues simulations. I tried to react the wick but it's still the same problem: it's serious at the beginning but the more it progresses the more it doesn't serious anymore. What could be the problem? THANKS