[Chas]

This is a rusted chassis. ANY grounds that are made via a rivet should be soldered to the chassis, use an active flux and a large soldering copper, preheat the chassis to get solder to flow.

A wiring error in the electrolytic can be a problem check those connections. Solder blobs, wire snips can cause shorts.

Check all RF/OSC coils for not only correct resistance but leakage between the coils. ANY leakage is an indication that celluloid liners have become acidic and are leaking between the coils. Cols will have to be rewound and insulated with Kapton tape or PETE.

Some tubes with grid caps develop a poor connection at the grid cap, re-solder...
GL
Chas