It's the rust that killed the new seal, you can sand the crank, but
it needs to be done with fine sanding cloth, at least 220 and use
oil as a lubricant, then follow up the rust removal with a very fine
like 400 also lubed with oil.
Rust is very hard, and rough which chews the fine lip on the seal,
the saver sleeve is another good option, but the rust is still going
to be a problem, also don't put the seal lip into the groove if one
has developed in the crank surface, drive it in a little farther to a
new fresh surface, past the rust if you can so it will not be a problem
Wild