Yes. I realized that shortly after I posted. In the tech's defense, we only had a telephone call, so it wasn't "eyes on". I gather that the Ansar Supersounds are polypropylene. I'm assuming, unless someone can tell me otherwise, that polypropylenes can go bad too and act in the same way (essentially, as a resistor) as electrolytics.
I find this theory about the problem highly plausible, because when I went back and tested the newly installed new tweeters again, the sound level was back to where it had been when I realized I had a problem, i.e., there was just a very faint, throttled sound coming from the tweeters, pretty much no matter what the volume on the amplifier was set at.
I find this theory about the problem highly plausible, because when I went back and tested the newly installed new tweeters again, the sound level was back to where it had been when I realized I had a problem, i.e., there was just a very faint, throttled sound coming from the tweeters, pretty much no matter what the volume on the amplifier was set at.