The firearm in question is a New Model Blackhawk chambered in .30 carbine.
I took it to the range today, and I was having issues with cases not ejecting. I removed the cylinder and gave the chambers a quick scrub. When I went to reinstall the cylinder, I got the base pin STUCK. I don't mean stuck like mumble obscenities while working the pin until you get it loose stuck. I mean, that sumbitch ain't movin' at all stuck. I even tried removing the base pin latch assembly to make fighting with it a little easier, and no luck.
When I got home, I grabbed my vice grips and wrapped the jaws with duct tape to prevent scratching or marring up the pin, I removed the ejector assembly, I clamped down on the base pin with the vice grips, and I pulled it.
Inspecting the gun and messing with things a bit, I can't see what the problem is. There's no meaningful sediment, and there are no visible burrs. The pin itself looks straight and symmetrical with no notches that need to be aligned. Sometimes, I can get the pin to drop right in, most of the time I hit major resistance and pull it back out.
What do I need to be looking for here?