Hit by lightning?
 

On the workbench yesterday was a forlorn GE model 516F, seen here:

http://www.radiomuseum.org/r/general_el_516f_516_f.html

After pulling the chassis, I noticed that one of the original .05 caps was internally charred badly, and crumbled like charcoal. Whatever caused this, the cap must have poured its contents out the one side forcibly, as there's a lot of fine gray powder under the chassis in a streak emanating from the capacitor. The rest of the caps were the usual blistered-looking wax originals. Replaced the rest of the caps, including the main electrolytic, but still have no power, going to test it further tonight.

I've never seen a capacitor look more like a blown roman candle. What the heck would have caused that, perhaps a lightning hit or a power surge?

May have been from a nasty voltage surge.

I was working on one that seemed OK and had it playing while getting ready to recap it and heard and watched a cap burp and spew wax out one end. Cord yank.

Had something similar happen with my RCA 9-T-246. Paper cap went BANG smoked and leaked wax.....Boy was I scrambling for the power switch on that one.

Usually the first wax paper caps to pop are the ones fron the 120 volt line to ground. These must be replaced along with the filters and coupling cap on the G1 of the audio output tube.

Had two do that to me in testing before, no bangs, but alot of gurgling noises as the caps blasted their waxy guts out onto components nearby, and yet, the radio kept playing merrily as I reached for the power cord.

Had you not unplugged the radio when you did, there might have been even more damage to the radio than a few blown caps.

I'm very surprised the radio continued to work even while the capacitors you mentioned were destructing. Apparently, none of the defective capacitors were power supply filters, as you did not mention AC hum in the audio; however, if the filters were acting up this way they probably would have shorted and tripped a breaker, since they are in a position to short the power line directly to ground if defective.

Good ones!
Years ago I was monitoring c.b. ch. 19 with a thunderstorm close-by. All of a sudden there was an arc/spark/bang at the antenna terminal-was a nearby lightening strike. Unplugged immediately. That c.b. still works flawlessly (an old Royce).
We die of different causes and ways-so do cap.'s.

I had replaced the supply filters prior to the bypass cap letting itself go. usually the first thing I do before plugging it in. That cap was a hard shelled plastic one too! (A white Sangamo cap), that came out /very/ hot. Surprised it didn't split and explode like the bumblebees do.

I'd agree with that. If it was a lightning strike, you'd probably see more damage around the power input (this is an AC/DC radio, right?). Where was that blown-out cap located?

Oddly enough, I just replaced all the capacitors in the set, and it came back to life. It's in my mom's kitchen now :)