I did some reading about Tokarevs and it appears that this is a common issue. There is something about the internals that makes racking the slide past the half-cock position on the hammer difficult. You can take apart the fire assembly group and polish a few parts and grind down a few others but that's beyond my abilities.
Playing around the pistol more this morning, I found that I could rack the slide by placing my left hand towards the front of the pistol and basically using the entire hand (as opposed to simply gripping the back slide serrations with my thumb and index finger). Problem solved. I think.