I'm beginning to get paranoid now. I bought my 57s from Pete MB&D of this parish, some 14yrs ago, and have done nothing to them since. I'm not sure how long Pete had them for, or what was done to them when he had them, if anything. They do have the clamps fitted (I think...) so they must have been serviced at some time in the last 50yrs, but as far as I can tell they are working just fine. To be honest, I just don't notice them, they are part of our TV system now, and the sound is so good we just don't think about the sound when watching films and TV, though we don't watch much of either as we listen to too much music.