Speaker Re-cap. How do you know when?

Howdy. Looking for input on speaker capacitors & their life span. I have a set of Infinity Renaissance 90's and the bass seems to be thinner than it used to. Thinner meaning not as strong, feel it in your chest type bass. The speakers go down to 27hz, so I know form the specs and experience that it can happen. Reason I am asking about the capacitor, is "back in the 70's", I had a pair of Pioneer speakers that occasionally would literally blow the insides out of a cap. I'd go to Speaker City grab a new one & solder it in till she blew again.
Question; Is there a chance the caps are old & hammered or am I searching the wrong area? What have you folks experienced? Are there even caps in the woofer cross-over’s?
Speakers are powered by Krell KCT pre & Krell FPB300cx.
PS - The surrounds look like new.
Thanks for any input and advice.
-John