You just may need a new bulb in your current projector. They start to dim when they need replacement. If the projector has been bright enough for you for 10 years....it's probably your bulb.
Projector Advice
I need a decent projector, mostly for static slides (powerpoint kinds of stuff rather than video). It will be permanently moutned in a decently bright room though in an alcove where there is less light. We have used a 3000 lumens projector for about ten years but it seems dimmer than it used to be and the colors were never very clear. The throw distance is 20 feet with a 12 foot screen. Looking at something around 4000-4500 lumens and operating on a small budget of about $1000. Any recommendations on a good projector?