I had a drift (I think it was a hammer head) about the right diameter and hit that to drive the seal in, if it is out of square you may need to knock it back out then drift it in square.
A thin walled socket that sits inside of the seal without disturbing the spring tensioner works really well..be gentle and tap it in little by little. I will check the socket size tomorrow.
'72 95 (The Flying Banana),'72 96(Bridget),'73 96 (Vernon),'74 95 (Veronica)