[Jeffhs]

I would definitely replace the 3-section electrolytic cap as a matter of routine. As for the spark when you plug the receiver into AC power, that is a red flag if I ever saw one--there is definitely a short somewhere, and probably close to the input to the power transformer. I'd replace the cord first, before plugging the receiver in again. The S-53 dates back to at least the 1950s; yours may well have a dry-rotted cord that should have been replaced long ago--you will get a huge spark as you described if bare wires from the cord short against the chassis or each other, although I'm surprised the house fuse (on that circuit) didn't blow as soon as you saw the spark. I had a floor lamp in my apartment that shorted out from the same cause (bare wires shorting against each other) a few months ago; I saw a huge spark at the base of the lamp, after which the circuit breaker in the basement of the apartment building tripped.

When you had the receiver plugged in and switched on, did anything on the chassis (power transformer, filter caps, etc.) feel abnormally warm after the set had time to warm up? If the transformer felt extremely warm or so hot that it would burn your fingers, pull the plug immediately. The transformer is either shorted (a high-resistance short will not blow a line fuse, but a low-resistance short will) or else something in the radio is drawing much more current than it should. If the filter caps are warm or hot, yank the plug as well, as the capacitor(s) is/are dead shorted--these capacitors are in a position to blow the house fuses (because they are connected effectively directly across the AC line) if they short.

If the short in your S-53 were anywhere after the AC input, it should have blown the receiver's own fuse if it has one, which it should--Hallicrafters communications receivers were all equipped with a line fuse that will blow in case of any major low-resistance short, such as a shorted rectifier tube or a short in the power transformer, to name just two such shorts that should indeed blow that fuse if it's the correct size.

As to all but one of the tubes glowing when you had the receiver plugged in, that's a dead giveaway that the unlit tube is dead as a doornail and must be replaced. In fact, the unlit tube may very well be the reason why the radio won't work (if the dead tube is in an audio stage, for instance, you won't hear a thing from the speaker). However, until you at least replace the cord, don't plug the receiver into an outlet. As it is now, the radio has a dangerous short that must be found and corrected (not to mention being a shock hazard) before the set can be used.

Kind regards,