I have a Larken System 600LS with dual lead screws. I'm getting chatter mostly when cutting circles and some angles. Cirtain places seem to be worse than others. I do mostly 2D cutting and it doesn't seam to matter if it is 1/4", 1/2" or 3/4" material. I cut plywood and MDF. Is this an issue from the lead screw nuts, drive motors or controller?