B&W and deteriorating Kevlar drivers

I have a pair of B&W 802N's purchased new when they first were introduced. Over time I had noticed a slight "card board" sound in the upper midrange that seem to grow over time. Just replaced the Kevlar midrange drivers and the distortion left........they need some break in time, but I think I solved the problem (not the cross overs). They certainly changed color over the years from yellow to almost orange. I would recommend the replacement of the midrange drivers if you have the original 800 series.

Anyone else have this experience?