Turn the purifier off and unplug it from the electrical outlet.
Remove the back panel from the purifier using a screwdriver, exposing the ozone plate and other internal workings of the Bentax P2000.
Mix one part ammonia and one part water. Dip a soft cloth into this mixture and use the solution to clean both sides of the ozone plate and all other surfaces on the ozonator.
Vacuum any dust from inside the air purifier using the soft brush attachment on your vacuum.
Plug the unit back in and test it. Sometimes removing the dust is enough to get the unit working again. While the unit is plugged in, note any other problems with it, such as a noisy fan or a non-working motor.
Unplug the unit again. Open the fuse box inside the purifier and replace the existing fuse with a new one. A one-amp fuse should work, but if the purifier uses a different kind of fuse, replace it with that fuse type. Check the owner's manual for the correct size fuse.