Hi,
I have a cheap CMS with a laser. It is badly positioned (at the back) and when you cut wood, it shoots ALL the dust / chippings at the laser. This is incredibly hard to clean, because it's recessed a little. I have a solution!
Give the laser a good clean, (toothbrush, cotton bud) and then apply a small piece of sellotape (see-thru sticky tape). This then gets rid of the recess, and is easier to clean. This in fact works like a filter on a camera for all of you who are photographers :)
Sam