I'm having some problems with Czerny Etude no. 22 from op. 299, with repeating notes, like these: And these in the left hand: My teacher explained something about the repetition system of Erard or something. She also said something about repeating while the hammer is half down, but not too much, because otherwise the distance is too short and the tone wouldn't sound or something like that. I can do them slowly, but when I speed up, I either can't do that (left hand) or get stress and there are many notes that don't while I press them (right hand). Can anyone help me with repeating notes? Practising slowly doesn't seem to help, because of the hammer half down thing I guess.