Zenith Advanced System 3 picture tube testing

[zeno]

An odd symptom. If it comes & goes try light tapping
of the CRT neck & see if it flashes. Can also swap the
transistors around & see what happens. Also run your tester
up a little on the filaments & see if it smokes out leakage.
Try it at 8V. These sets did some strange things when the
CRT's were bad.............

73 Zeno