I've had another go tonight, I've tried knocking the opposite side of the crank, I've tried screwing the new retaining ring in but there not enough thread there to get it to stay, I've tried removing the screw and riding it round for a bit and I've tried screwing something into it and knocking it through the drive side. None have been successful.
I'm thinking that maybe a bearing puller will do it but I don't have one so need to find someone who does. For a system that is meant to make removal easier, I'm disappointed
