Slight amount of heat and a hydraulic press should do the trick. Hammering with no immediate results will do more harm than good as you smoosh the pin actually tightening it in the hole.
If you're going to pound on it you should "whack it like a baby seal" as they say. Provide plenty of support to the casting, in this case you might could use a heavy pipe that the pin fits loosely in, supported on an anvil or concrete floor.
Grigg
