One of the problematic zones of some very old Sound Lab speakers is the contact between the connecting wires and the resistive membrane - made using a strip of aluminum sheet at the bottom of the panel. Sometimes the mylar membrane becomes damaged at this zone. Carefully listen for any noises in this zone.
I still keep the tweeters of my 30 years old A2's - although the bass panel suffered from this problem, the treble panel is still playing perfectly!
A friend of mine has a pair of A1s from the 80's playing perfectly.
I still keep the tweeters of my 30 years old A2's - although the bass panel suffered from this problem, the treble panel is still playing perfectly!
A friend of mine has a pair of A1s from the 80's playing perfectly.