Total posts : 45366
Not sure what you meant by blasting the AM but if you meant increasing the audio voltage by turning the pots on the SSTRAN a couple of things could be happening.
With age, pots can develop a dead spot where the wiper contacts the resistance element. Turning the shaft can wipe the spot clean or result in parking on a good spot in a different location.
Another thing which happens with bad connections is increasing the voltage sometimes “fixes” the problem (or so it would appear though it is not a fix). Most metals develop a layer of very thin oxide or corrosion when exposed to the air. This can take a long time and the layer is very thin but it is thick enough to form an insulating barrier to current. Raising the voltage breaks down this insulating layer as the voltage “punches through” and burns the layer away. The voltages involved are low, on the order of tens or hundreds of millivolts, but can be sufficient to burn through.
Designers of switches and connectors which do not use gold plating deal with this problem by providing a wiping action when the devices are operated or mated which scrapes the oxide away. This is why unplugging and replugging a connector or operating a switch many times will fix the problem.
Now, back to a bad solder joint. This same effect could operate with the joint and increasing the voltage could be a temporary fix. The permanent fix would be to resolder the connection.