Is it working? The best way to clean the laser is to take the top off the machine (unplug it first!!) and the lens is immediately apparent and can be cleaned with a cotton bud and so isopropyl alcohol.
I doubt that a dirty lens would stop it from working though.
Service is tricky these days as many service departments have lost their old staff and now repair by replacing modules. The laser is no longer available but the problem is often a simple component rather than the laser itself.