[Mondial]

The cap connected to pin 6 of the 12AU6 ( 12BA6?) looks like it is C13, a screen bypass cap. It appears from the color code to be 2200 pF, (.0022 uF), which puts it pretty close to the .002 uF I read on the schematic for C13.

What did you measure the mystery cap's value to be? It definitely looks like an early molded paper cap, with the resistor color code used for indicating value.

Edit: I looked at the photo again and it looks like the mystery cap is connected to pin 6 of the 12BA6 first IF tube. It appears that the second IF 12BA6 also uses the same .002 uF screen bypass. The 12AU6 tube should be the limiter, connected to the discriminator transformer near the 19T8.