The sheave of the genoa turning block on my Sigma 33C has died, and so I fished it off the boat. At first I assumed that I would be able to press/whack the pin out, but this proved to be the wrong answer.

I found this thread, which illustrates the issue:

Mine is a single, rather than double, block, but of the same make and vintage. However having ground off the peening at the bottom of the pin it is still stuck fast. Unlike in Javelin's case there is absolutely no movement between the pin and casting.

So my question is: how do I go about freeing the pin?