Finally I got my motor shaft removed.
It was completely stuck. Even with heat I wasn’t able to get it off.
The only solution I found was to drill straight through the shaft and insert a pin. The shaft together with the pin was then clamped in a vise. That way the vise had something to hold on and the shaft couldn’t spin in the vise anymore.
Then I took two screwdrivers, inserted them in the holes where the grub screws were and used them as leverage.
By continuously rotating the bell I could finally work my way up.
Interestingly there wasn’t any loctite holding the shaft. It simply was an extremely tight press fit.