Picture too dark. Particularly noticable during night scenes in movies. Adjusting brightness all the way up helps, but not enough.

Hi,
Try to claen the top of three crt guns inside you tv. also the reflecting mirror behind the screen.
one more thing you have to check, that is the CRT base sockets. After some years of use its contact will become bad. As there is three crt guns there will be three crt base sockets on the neck of each. Replace all the three crt base sockets at the same time. It will improve picture quality.
ok