A lot of people dont realize this so just in case...
Zeniths can & do get bad connections. The ends of the strips
are the grounds & sometimes break loose. There are also sometimes
grounds along the strips. Not common, the first one drove me nuts !
Finally the boss saw it & told me. Seemed to happen mostly up
under the jug on the left. Most common on 18" tin cans & other
sets of the late 60's.
73 Zeno