You could try heating up the pinion. The metals are probably not the same, so will have different expansion rates and may be easier to remove...

I can try to heat it, but have no idea how to hold onto the gear. I could clamp it into the vice??? Then use a punch to tap the shaft out of the gear...

If it was me, i would stay away from any treatment involving heat. It might undo the heat treatment that the shaft probably received hence weakening it.

True, I ended up grinding the pinion on both sides and then split it with a pir of pliers. Easy when you know how...