35 year old drivers need replaced?

Assuming no abuse over the years (played too loudly or with a clipping amp, etc.), the things that deteriorate most with age in a speaker are:
- driver surrounds. This is most pronounced with foam surrounds. If damaged, it will be very obvious. Other surrounds may still be fine -- I have a set of KEF B-110 mid-bass drivers from 1979 and the surrounds are just fine.
- electrolytic capacitors in the crossover.
- ferro fluid in tweeters can dry out. Many tweeters do not use this fluid. Check if this applies to the tweeters in your speakers.

mlsstl has not left anything out.

Interesting speakers by the way!  I’ve had dozens of speakers but never a pair of these... yet 😁

mlsstl nailed it! +1

Hi,
why change drivers, don't you like the speakers as they are?
You altered them with Mundorf caps (i am not a fun of Mundorf -:)). Assuming the rubber sourrounds of woofers are fine the only thing that may need attention is the ferrofluid in the tweeters.