The popular b&o speakers made in the 80s are still sought after my many audiophile today and in good condition can fetch a good price, however there are some models with a drone ABR unit and the problem is that NONE have survived over 12 years or more, the problem is the ABR units which is approx 10x4" in diameter made from foam deteriates over time to a point where they are totaly gone, this ABR unit is vital in the speakers ability to produce lower end frequencies and without it the speakers will only sound at best 50% as good as they should.
I would say 90% of the redlines with ABR unit produced have rotted.
The b&o 60.2 does not have an ABR unit.
The repair of an ABR unit is pretty simple if you can get a sheet of thin but strong foam, the foam should be cut using the original ABR housing as a template, once cut, the foam has a thin steel plate stuck to the back of it, this gives the foam weight and helps with resonance and stability.
If someone is selling a pair of redlines and they say they are working, it might pay to see if the ABR units have been replaced, more times than not the seller will not even know or realise they are perished but you need to ask as the ABR unit is a vital part of the speakers system and its ability to produce bass, without the ABR units intact the speakers will be bass-less and sound awfull.