I agree with everything stated above, however, (and you'll only not do this one once) while you have everything disassembled, run your fingernail along the surface that the new seal is going to ride on, if you can feel any wear, take some emery cloth to it and polish it up. I mean you'll only not do this on once beacause if there is wear, or a build up of crud there and the new seal does not seal as a result (meaning you now have the "oportunity" to do it all over again), you'll never forget this. Also, make sure and lube anything that will come in contact with the new seal well for reassembly as not to tear, or distort the new seal.