@jimijam good for you, however, I did read this blurb on a site selling replacement polycaps for the AR-9 (I have a set and plan on opening them up to see which capacitors were used. Mine are circa 1982, so I don’t know if they might be Callins or Sprague, but I’ll find out).
Blurb: "Do you need these capacitors? Twenty years ago, when we began servicing these speakers, there didn’t appear to be any need. However, perhaps ten years ago, we began to find capacitors manufactured by Callins Inc. installed in other AR speakers that were way out of spec. That created concern for the AR 9 and AR 90 speakers and we began finding them in these also. In recent years, customers have been requesting this kit for their speakers, particularly needing them for the tweeter section.
However, even though some larger Callins capacitors may be found in the woofer crossover section, the impact does not appear to be as great. Now, if you have a late production pair of these speakers and find your capacitors to be manufactured by Sprague Electric, there is no need to replace them. We have never found a Sprague Electric capacitor to be out of spec."
Apparently the worry is that an out of spec capacitor could cause you to blow your tweeters by feeding more power to them than you think you are, tweeters that can’t be easily replaced, if at all.
I did have the surrounds on my drivers replaced 15 years ago with butyl ones that should last "forever", but was dumb and didn’t document the crossover components back then.