To avoid hijacking the original thread - I note these concertinas appear to have washers on the end bolts (screws?). I don't recall seeing them on many others, whereas I've both seen and heard of Lachenals etc with the bolt heads gradually burrowing their way through the end plates.
This ad is currently on Gumtree....
Need I say more....?
Have I just got it wrong (it's been a long week) or is there a reason they're not used?