[codefox1]

Great!, all that I can add is sometimes there is an accumulation of dust or whatever between the voice coil and tne pole, especially in reall old speakers that did not have a felt "dust cover" element. ever so timid compressed air may fix this. Ancient remedies included having the speaker face down and induce a weak 60 CPS voltage to voice coil (whilst also energising the field coil if it is not a PM type) an let the dust gravitate out and simultaneously flex the cone to reveal tiny tears and whatever.