It has come to my attention that some digital projectors (this includes both DLP and LCD) are prone to developing some problem that gradually worsen and may not be noticed. The changes are slow enough that you might not notice that 30 to 40% of light output is lost despite the bulb continuing to work. 1. The reflector portion of you lamp houseing may deteriorate faster than the bulb itself. The reflector is the parabolic, aluminized mirror that concentrates the light of the bulb. It looks much like the reflector in a flashlight. While some gradual oxidation and darkening is expected during the lifetime of a bulb, some reflectors are developing many fine cracks (crazing) as early as 200 hours operation. 2. DLP color wheels may become severly hazy. You can usually see the color wheel by simply pulling the lamp out of the projector and shining a flashlight into the bulb chamber. The color wheel should looke like shiney, color glass. If its surface is hazy or foggy, a large portion of light from the bulb simply gets reflected back to the lamp. As much as 30% of total light output can be lost if the color wheels become heavily contaminated. The contamination appears to gradually worsen on those machines which are prone to the problem. It can become so bad that one cannot see through the color wheel. I think it prudent for all digital projection owners to periodically pull their lamps and inspect them for reflector deterioration (and color wheel contamination if your machine is a DLP). Every 200 to 300 hours is a reasonable interval. Take care while doing the inspection because damage caused by you is your own responsibility. At the very least, inspect before your lamp warranty period expires. Always allow the projector to cool prior to pulling the lamp assembly. Instructions for pulling the lamp should be in your manual where it describes user lamp replacement procedure. Do NOT touch any lamp or projector glass surfaces. Do not attempt to clean the color wheel or lamp housing yourself unless you are willing to assume the risk of damage. Some less understanding manufacturers may even void your entire warranty if you perform your own cleaning. Call the manufacturer service department and ask for warranty service of affected machines.