As previous poster almost said, cap replacement would be an avenue. The drivers are probably fine, with their heritage being JBL. I have taken apart a dozen JBL crossovers, and what they use for caps is fine. But ... the best caps for audio are likely 10 or 20 times more expensive than the caps used in the revels. I am guessing, but its based on a lot of experience. But you might get an improvement. What I would worry about would be the caps themselves being big enough that the cab displacement is changed ... but in a big cab like that, probably the issue is small. So, if you have the skills, try it. If it does not work, put the old caps back in.
