The belts and pulleys in your laser system can become coated with smoke and residue and should be cleaned regularly. I have a small tool kit of cleaning brushes and some canned air near my laser to blast out and brush away buildup that may cause a problem with any mechanical components. The brush selection includes several toothbrushes. I also keep a 2-inch wide economy paintbrush handy for larger areas and messes. One cleaning tip is to leave the laser system off while the exhaust fan is turned on. Carefully move the mechanical components and brush any residue into the exhaust plenum.
-Mike Fruciano, Coherent