Use heat, then pull real tight.
When at the limit of your "feel", tap with a steel hammer. You need the sharp shock wave that the hammer provides. The risk is in that you will also dent your front ball bearing.
A steeper taper would help this problem, but then many people complain about the taper popping loose without any effort. Personally, I like the steeper tapers, because I dismantle engines frequently to check on my experiments.