[NostalgiaRadioTime]

There's a black rubber wire on pin 4 of the 50L6 tube, but it is disconnected on the other end. Can anyone tell me where it connects? Thanks!

[BrendaAnnD]

Pin 4 on a 50L6 is the screen grid. According to the schematic, it's connected to one of the filters and to one side of the speaker field coil. That wire could well have been going to the speaker field coil.