I have a pair of L200's I purchased about 12/13 years ago. I know if the woofer surrounds are foam you should rotate them periodically to prevent sag. Is the same true for cloth surrounds? If so, what is the frequency? I also have a pair of L96s that I refoamed the surrounds on at least 15 years ago , should I rotate those,also? Understandably gravity is well, gravity. TIA ,Marty