Widget,
You might be surprised how well a hot air gun would work here. You might have to keep the heat on it for 15 or 20 minutes as all that metal will soak up the heat. But you'll have far better control with that seal there. And only 50 bucks for a cheaply zit brand one at bunnings. Ideally you'd want the heat in the part your trying to remove and not in the shaft and so perhaps the fast heat of a flame thrower has some appeal in that regard but the heat control of the 'hair dryer' has some advantages too. To that end it is my first choice in situations like this.
Just a thought
Just a thought.
