I had an older(late 90's) Celestion V10-60 that had been sitting in box for a while because I started to find it to be too dark sounding. Yesterday I decided to take some of the doping off the surround, which looked pretty thick. I used some acetone with an old tooth brush, wiping the excess off on to a paper towel. The end result was fantastic! The bottom end still sounds great but the top end really opened up, sounding nothing like it did before. The lower mids seemed to have calmed down a bit, so the speaker sounds more balanced. I'm not sure but speaker might have lost some output power but it sure breaks up sweetly now.