A few weeks ago, in the middle of cutting vinyl, my machine started making a noise in the tool carriage...it sounds like something is loose. Since then nothing cuts cleanly. It cuts all the way thru but now the lines and curves are best described as wobbly. I've tightened every screw I can see, and adjusted both the speed and pressure, and also changed the blade, but nothing has worked. Does anyone know what the problem might be?? Thanks!