check wich one is leaking u can do it just take the ruber boot out and see if it wet,
if it is just change it no abjustments needed with new slave but with master u can abjust your clutch on the pedal just loose 12mm nut twist the shaft one or another way and better replace both of them at same time because if u relace only one different pressure betven old one and new one may cause leak the one u didnot replace i had expirience