I guess U checked status of brightness and contast controls??? Not familiar with xistor circuits. Check both areas (bightness & contrast ) as have effect on brightness for possible faults. WOW , I have seen a hybrid set in ten years. The guy had a Zentih that didn't work. TV was his baby, even tho didn't worked. Probaly still sitting in his garage!!!!!!!!!!!!!
Familiar with solid state?? Keep this tv as most early solid states are thrown out already!!