I use a Lisle 58340 Seal Remover for this type work.

Lisle Seal Remover

The other trick is to cut a piece of plastic from a pop (or soda if you live in certain geographic regions) bottle. Wrap it around the OD (the sealing surface on the nose) of the crank and slide it back under the lip of the old seal. Then slide the tip of the tool under the lip and over the top of the plastic.

The thin layer of plastic protects the sealing surface of the crank.

Rusty