3200MP -- lamp fine, but no BLUE colors being projected

we have a 3-year old 3200MP projector. It was doing great until about 4 days ago. The light was flickering and colors would fade out leaving us with only Green and Purple colors (plus B/W). We thought "lamp needs changing". So we changed the lamp. And got the reds and blues for about 2 minutes. And then it faded out again. We've reset Factory Settings several times. Made sure it's not the computer and cord (switched them out.) But notice on the projector, that if we had or subtract blue color, nothing changes. Basically, blue is gone. Anyone know what is going on, and how to fix it?