As long as you cut your materials clean with the right air pressure, the right amount of vacuum, and you have a clean workshop, maintenance is low. You always want to check if your lenses are clean, but you should have enough air pressure to keep the lenses clean. A lot of people cut with too little air pressure, and there will be debris that gets back up onto your lenses and that will cause a bad lens.
Other maintenance on the machines are typically done once a month, such as oiling or greasing the machine. Make sure your table is clean and free of debris.
-Adam Voigt and Eric Johnson, Kern Laser Systems