Some tips I saved from earlier posts on this subject. Haven't tried them yet as I drilled mine out. I did drill and tap that hole with a 10:24 and use a button head set screw. Adjusting it really improves the cast weights on the front cavity of a Lyman DC.
Heat the mould really hot, then hold a piece of dry ice (with tongs!) against the pin for a few seconds, then try pulling the pin out. You might get away with using freezer ice, then again you might not.
There's also an aerosol product called Freeze Off which is a penetrating oil propelled with something like what's used in wart removers, i.e. it gets stupid cold when it depressurizes and evaporates. It's used for shrinking stuck parts, like pins. Freeze the pin, lock it in a vise quickly and crank on the mould block with a padded wrench. Or grind it flat, center punch it, and drill it out.
The pin is 5/32 diameter. It is pressed in. It is dead soft metal. Snug the pin up really tight in a knurled vise, Use a plastic (or other) no-mar hammer to tap the mould blocks away from the pin while supporting the blocks with your hand to keep the pin from bending. Alternately, you can grip the pin with vise-grips, heat the block slightly and twist it out. Once the pin (now destroyed) is out, you can use a roll-pin as a replacement.
Vise grips work well. If you don't crush too tight the pin can be reused. I grip snugly with the vise grips, get a flat screwdriver and pry the tip up against the vise grip jaws while twisting the pin. Use piece of sheet metal on the blocks to protect the top surface and don't pry with the tip pushing into the face of the blocks or you will be cleaning that up after some inventive speech.
