I have been having real problems playing Cornet over the past few years. I was principal Cornet for 20 years in our village Band and played Besson cornets, the "Imperial Besson" predecessor to the 700, then my own Sovereign possibly a 921, and then a 927. More recently I have mainly conducted or played Euphonium. Around November it became clear we were short of Cornet players and I dug out the old Sov. Actually I went through all the spare Cornets and found a 700 was easiest to blow and sort of struggled through, though I ended up playing Horn on most Carol events. Now Christmas over I put the 700 back in the Bandroom and I idly wondered why it played so much better than the 927. The Instruments looked identical except a mobile 1st slide on the 927. Even the valves interchanged. So I swapped them and suddenly the 927 blew easier. I was intrigued, so I swapped them back, checked the felts, which were actually very thin, so I backed off the Valve caps, not finger buttons, off a turn and the 927 blew much freer, especially on bottom C but noticeably better all round. Further investigation showed the valve threads were two threads or thereabouts longer on the 927. 10 minutes work with a sanding disc in my black and decker drill and they were the same length as the 700 and it blows much better with everything screwed down. I checked the old Sovereign a 1980 built model and it also played much freer with the valve caps loosened, and yet with the slides pulled I could see the valves still lined up perfectly with the valves down so after establishing how much the valve needed to be shortened I did that too, and it transformed the damned thing. I had been playing it since 1990. Which leads me to wonder just how many poor instruments just need a bit of physical adjustment, and what if any quality control existed at the old British factories. Maybe some other players have this problem without realising?