I have a Campy 10 speed Record groupo with about 2500-3000K on it. I have been keeping an eye on the chain stretch with a Park chain checker and a precision ruler. I just got into the cusp of the red zone on the Park tool and the ruler shows 1/32 stretch on the chain. So I know change out the chain. I am now getting a grinding feeling and some chain jump/skip under hard pedaling. I don't know what to think other than that the cassett is shot due to using a worn chain. So why does the old rule not work for a Campy 10 speed chain ware? When I was shopping for a new cassette , I read that 1600 miles is tops for a 10 speed chain! Is this true? I have been road riding since 7 speed and never ran into this problem. Whats the deal??