Brief update....
So I soaked the lock for 24 hours in an oil (I used 3-IN-ONE Fast-Acting Penetrant) for 24 hours like Bob Roller suggested, although I did not take it apart, and I took it out tonight and scrubbed a little more with a toothbrush. Didnt seem to do anything at first, so I decided to just work the cock...back and forth, back and forth, back and forth.....and then all of a sudden it held in half-cock, which it had not done before. I released it and tried again, and it didnt work, so I worked it again, back and forth, back and forth, etc... and it held again. I was able to repeat this about 10 times in a row where it held both half-cock and full cock just fine, and then....oddly.... it held half-cock but wouldn't properly get into full-cock. So I released it, worked it some more, and then it worked about 7 or 8 times perfectly before not achieving full cock again. So I put it back in the oil as I'm hoping that perhaps (and this might be wishful thinking) there's nothing wrong with it and it just needs time to eat away at all the fouling and filth that built up while sitting dormant for god only knows how many years since it's last been fired. I thought about putting it back in the oil at full-cock figuring that might slightly expose a bit different surface area, but I wasnt sure if it's good for the spring to leave a lock in full-cock for 24 hours.