Who else owns a Grundig Satellit 210?

[ctc17]

This is a common problem I hear on allot of old equipment. I have come to the conclusion its due to the speaker cone becoming soft from humidity and use over the years.
I maintain the sound system in a rather large nightclub and I recone the speaker. The cones defiantly become very soft over time and they start distorting/bottoming out just as you describe.
I know a radio/tv speaker doesn't get the abuse of a club, but some of the cones I have felt on some of my 60s tvs and radios are so soft they feel like tissue. I have even gone to the point of putting a small 22/47uf cap in series with the speaker on some of my old radios to filter out the bass.