Selenium rectifiers in Zenith radios

[Jeffhs]

I have two Zenith AC-DC AM/FM table radios from the 1960s; one, a Zenith C845, is pictured as my avatar. They both work amazingly well for their ages, and still have the original selenium B+ rectifiers. The seleniums in these radios are quite small. What are the chances of these small rectifiers shorting after all these years? Since these seleniums are so small, they could not have had to handle that much current. I can see having to replace the large seleniums in TV sets (like the ones in my folks' second TV, a 21" Crosley console) after 50+ years, but the tiny ones in radios? These radios do not draw more than 35-40 watts at most from the AC line, so these small rectifiers should last indefinitely unless there is a power surge, a short in a filter capacitor, or some other problem that sends too much current through the rectifier. In all the time I've been in electronics (40+ years as a radio amateur), I have never even once smelled a defective selenium. Do these things actually give off a toxic gas (as I have read) when they short or become defective? I would think that if they short, the house fuses or circuit breakers would open immediately since they are in a position to short the AC line directly to ground.