Stuck woodruff key on water pump shaft

I have a Yamaha 175 HPDI 2 stroke. I removed the housing on the water pump to replace the impeller, however, I could not get the woodruff key to come out. It is stuck firmly into the shaft, and I need to remove it in order to replace the gasket below the impeller. Any suggestions?

[boats.net]

Try to remove key with a pair of wire side cutters, sometimes have to drive it out with a chissel.

If very carefull use heat and tap out with screwdriver.
I have used a gas handheld soldering iron with tip removed to give a small but easily directional v'hot flame jet.
hope this helps