I realise that this may be a strange request but a very good friend of mine recently had her round stamp horn serviced. When she got it back she noticed that the resistance had increased so much that it made almost imposable to blow. On close investigation she found that the horn had two third valves. She bought the horn second hand a long time ago and has played it for many years with great success. Is it possible to source a second valve for this instrument? She has already contacted the people that undertook the service to see if some other poor horn player now has two second valves.