Issues with these besides silver mica disease is the 6E5 eye tube being dim to dead and wacky FM reception due to the German-made (via general instrument) 12DT8 tuner. I have covered the tuner problems by way of posts in RCA, Motorola and Magnavox forums. Zenith and others also used these 1960-64 just before solid-state tuners debuted in Magnavox.
The tired and rare 6E5 can be replaced 1 for 1 using a very-common test-equipment eye tube type 1629 provided the following modifications are made;
1. 6E5 uses 6-pin socket, 1629 is 8-pin octal, this is a no brainer, just consult a tube manual for the pinout. Target resistor is still 1 meg
2. 6E5 has 6.3 volt heater, 1629 has 12.6 volt heater, to boost and make it DC, use a doubler circuit formed by two 1N4005 and two 1000 mf caps.
Worked like new using AVC input voltages, closed fully only on strongest stations
