Most of the time i take off or cut off the bad boot that is cut or ripped. i save the clips just incase. i then take the shaft and clamp it in a vice. Then i take a punch and hit the gear thing attached to the main shaft. put the punch right next to the, ain shaft when trying to knock it off. sometimes they have a spring clip that you can undo to slip it off.
Also check youtube...they have videos oh how to replace a boot!