As the stock breaks when you hit the impact. These things are fragile.Good information there Flint62Smoothie.
The impact driver will do the job along with the penetrating oil IF you can get the screwdriver bit to fit the slot well and keep the bit in there when hitting the driver. You can also use a drill press to put downward pressure on the bit while you manually turn the chuck or pully. I like the impact driver method myself.