[klondike98]

Welcome to the Phorum. I see you have a schematic and that's the first place to start checking things. I've not worked on this model before but that black "tube" looks to be an electrolytic capacitor. From what you said it seems it was wired in but hanging loose under the radio chassis. That leads me to suspect it was added later to replace one of the original electrolytic caps that had failed. The indentation on the cardboard was where it was clamped onto a chassis at some time in its life. I'd replace all the paper and electrolytic caps as they appear in the schematic.