Hello, I'm newbie here and novice on Cor Anglais too. I picked up a JA Cor Anglais about 10 years ago. I don't think it's playing properly - maybe there's a leak, but wondering how much the instrument might be worth a) in its current condition where you can't get in the upper register reliably but there are no cracks in the wood, b) How much would it be worth if it were fully serviced and overhauled? c) how much to overhaul roughly an instrument like this? d) any ideas when it was made?