Procedure captured in photos below:
Photo 1: Bearing seat in top of headstock
Photo 2: Nifty wee bearing seat removal tool
Photo 3: Tool in place on top of headstock
Photo 4: Drift inserted from bottom of headstock
Photo 5: Couple of whacks on the drift with a rubber mallet and the bearing seat is out
Repeat at the other end to get the bottom seat out ... bit more tricky as this seat's diameter is about the same as the headstock inner diameter and may be flush into the shoulder, so next to nothing for the tool to grab onto. Expand the tool as much as possible and the first couple of thumps on the drift should move it enough through friction to get a gap between the seat and the shoulder it sits in for the tool to get a better grab on it