Do this outside, or in a well-ventilated area.

Take a heat gun and blow heat on the part for about two minutes to get it up to maximum temperature.

Spray the part with penetrating lubricant. It will smoke slightly, and it won't ignite.

If the lubricant evaporates, spray some more on, until the lubricant shows no sign of evaporating anymore, meaning that the temperature of the part has dropped significantly.

Repeat the heat - lubricant cycle three more times.

The idea is to break the bond between the taper pin and the part, and get some lubricant in the tiny microscopic gap in between.