What makes the volume of a transister radio, for eg., to go from loud to zero in less than 10 seconds or less, every time?

A faltering rheostat.

Ok. What would lead it to be faulty? Meaning what do you do to prevent a faltering rheostat problem?

Faltering rheostat problems are very few and far between. A replacement is in order to repair the radio. You can’t do anything to prevent a failure.

Old radio? Potentiometers can get scratchy and do this. A quick fix is to turn the volume all the way and off all the way a bunch of times with the radio off to remove the crud on the wiper.

This could also be a failing coupling capacitor between transistor output stages.

@kritiper I take it you mean you’re not aware of anything that would prevent it.

@ARE_you_kidding_me Not old radio. New enough to be mostly digital. volume and search for stations analog.
I’m looking into where the wiper is (images google is not giving me anything radio related)

Does it have a volume knob or buttons? The wiper is on a potentiometer.

@ARE_you_kidding_me I just came to this thread to add to my last post,and found your last post. No notified, on Messges for You”.
The volume and the tuning, not buttons. They’re analog, so whatever you call that’s not buttons.
@kritiper “Remove the crud on the wiper.” in @ARE_you_kidding_me previous to last post = prevent the problem by using clean hands it looks like.

@ARE_you_kidding_me Thanks for the answer.
I’m looking at image/diagram at:
https://en.wikipedia.org/wiki/Potentiometer