Thanks for that.
"It will still seal but not as well, it can start seeping oil as oil works its way through the crevices."
If it starts to seep oil is it likely to be enough to cause any problems - will it be noticeable i.e drips on the garage floor?
What's your preferred method for pulling the seal. I'm torn between screws into the seal and the seal puller in the attached photo. I don't find inserting of the puller through the lip between the seal and the crankshaft a particularly appealing prospect.