Look into the three tubes while the TV is running, and observe the
picture quality of the three. Usually, the red is crisp and clear, the
green somewhat (or really) hazy, and the blue's picture nearly
obliterated from bacteria growing in the coolant. If the coolant is
clear, it can be a weak CRT. If the images are as I described, the
problem is the coolant, which is a very common problem is Philips. The
blue and green CRTs need to be removed from the light box to be
serviced. The coolant needs to be drained, the CRT assemblies
disassembled and totally scrubbed clean and refilled, then reinstalled
and converged. While the red tube in Philips products doesn't usually
get cloudy, the fluid does yellow somewhat. I always service all
three tubes together.