What am I likely to hear if my speakers are suffering from the wear of age? There are so many parts to consider in the whole system, how would I guess for sure what the origin of various irritating effects might be?

Silent
Rattles
Buzzing
Humming
Popping
Raspy

Most old speakers had foam surrounds and paper cones. After many years of use, and depending on the climate, the foam surrounds can turn to dust as well as the paper cones. You should be able to tell if they are worn just by looking at the drivers.

Also, spread your fingers apart and with your fingertips, slowly push on the woofer cones. If you feel any kind of vibration through your finger tips, the voice coils may be blown.

Also, with the speaker playing, take the cardboard roll from some paper towels or toilet paper and put one to your ear and the other encircling the tweeter to hear if it is working at all.

Many speakers use electrolytic capacitors in the crossovers and those are known to change their value signficantly over time. Since there's no easy or inexpensive way for the end user to check them, I'd find out what their values are and replace them. Then I'd reevaluate matters.

Most old speakers had foam surrounds and paper cones.

I actually popped the cover off these (I haven't done it in years), and they did indeed formerly
have foam surrounds - now they have a pile of foam fragments down near the bottom.
Cones are plastic though, they look OK, but it is probably time for new speakers anyway,
who knows what other problems might be lurking (and besides it is my patriotic duty to
spend my tax rebate and help pump up the economy :-).

I actually popped the cover off these (I haven't done it in years), and they did indeed formerly
have foam surrounds - now they have a pile of foam fragments down near the bottom.


Yup. Those are usually the first things to go.