If the lamp is on in the back, it's probably not the lamp but something internal. You might schedule a service call to have the unit inspected. Unfortunately, it's difficult to diagnose without being there.
Iam not a tech head and I love my tv. However,it started freezing up and cutting off radomly. TWC tech came out and we eliminated them as the problem. I live in a rural area and can't find much help. Could it be a bad bulb? I can see it burning from the back of the set but it does not stay on and even when it is glowing in the rear of the set there is no picture/image of any kind on the screen.