I got some new tools a couple days ago and I've been trying them out. Worked pretty well at first, but then my practice lock just started acting... weird. Where it had opened fairly easy before, I spent a good 15 minutes raking it without progress. When I knew something was wrong was when I noticed that I couldn't hear any clicks whatsoever when releasing tension. At that point I put away my rakes and starting poking around with a hook. I couldn't feel any resistance anywhere. Now I've had bad days where even my cheap little Kwikset practice lock won't open for me, but I should at least be finding something. While it would normally feel cheap to call the lock broken just because I couldn't open it, something was wrong here.
I popped the little top panel off and sure enough, something was seriously hosed. One of the springs was completely stuck. Best I can tell, the end of it somehow got wedged between the key and driver pins. I ended up having to yank it out with pliers. Luckily I had a replacement spring laying around. Put it back together, and suddenly everything is perfect again.
So I guess the lesson is, I'm dang glad I was using a practice lock and not something that goes to one of my doors like I used to do.