if you mean the cymbals themselves are damaged you can -for cracks drill either end of the crack, which stops the crack travelling and cut the crack apart to stop the edges vibrating against each other do this with a small high speed tool rather than force a file into the crack because something that cuts cleanly will not distort the cymbal further- if it is minor dents, leave them larger dents can be removed with a plenishing hammer and a hard-ish back plate but unless you're talented and can match the existing standard it might be time to find newer ones- if you mean setting up the high hat there is a great tool for drummers "free drum lessons" search youtube enjoy
howtomendit.com for free repair help, information and advice.
