It is tough going until you are out about 1/2 inch. There is a large o-Ring that seals off the pinion to housing. It will commonly stick in the bore. Pry evenly around the flange, with discretion, and it should come out.
Matt
Spray it with your favorite loose juice and keep working it back and forth. Just remember, that flange can break if you pry with too much force. Over the years, some rust has formed in the bore the pinion housing is in. Probably some fine dust has gotten in as well plus the rubber O-ring has hardened with age. Keep at it. .it'll come out sooner or later.
You will also want to remove the end cover from the pinion. It will bump the governor housing. With the end cover removed from the pinion you have just enough room to slip the pinion out.
Thanks guys for the help. It now makes sense.