I have a 1976 (according to serial number charts) Boosey & Hawkes Imperial cornet. Overall, it is in nice condition, but the No.1 valve had been slow. I have just found out why (I hope so). I had thought that the valve plating was perfect, and after wasting a full bottle of valve oil cleaning, inspecting, washing out and re-oiling over some time, I think I have discovered the cause. I found a speck of corrosion on the valve, about 0.75mm across, with the chrome raised very slightly at its edges. I have gently smoothed the chrome off at the edges of the speck, and it seems to have done the trick. I don’t want to be stuck without a reasonable cornet again, and nor do I want to spend a lot of money on the instrument when that might bring its total cost to rather more than the price of replacing it. Does anyone know, please, whether this pitting is likely to get much worse very quickly, assuming a good cleaning regime?