I wouldn't get into the caps yet, there are a lot of them in the crossover. When you removed the front enclosure to access the tweeters, did you clean up the slip-on connecters and check if they have a good connection? If you didn't, I would check out those connectors first and make sure they aren't oxidized and they are all making a good connection.
Also, visually are the midrange drivers all in good condition?
Also, visually are the midrange drivers all in good condition?