Just to close this one out, after a largely unsuccessful look on the internet (only found one in California for an eyewatering price), I went the Barry Jackson route as had been suggested. As ever with Scotters, he was very friendly and helpful on the phone, and added me to his ‘to do’ list (I said I wasn’t in a hurry). I’ve now received a rather lovely (and very good value!) replica damper that looks an absolute treat on my top yoke. Really, really pleased….