After about 4-5 years of use in classrooms and as rolling stock we are seeing a blue and/or yellow washout effect with these projectors. We think the blue and/or yellow haze problem is because of several factors.
- Dust buildup inside the optics .
- Fading colour filters used in the internal optical process.
- LCD image degradation.
Inside the projector the white light from the lamp is split into three distinct colours of red, green and blue. Each colour illuminates their own monochrome LCD. Those LCDs are mounted on a prism that combines the separate images and displays the result you see via the lens.
The optical process to split the light up inside the projector is fairly complex and involves many light filters and mirrors to direct the light to the appropriate lcds. Those filters and lenses accumulate dust and also fade over time due to heat and other environmental factors.
Not sure if a fix is possible will post more info if any.