It’s probably just something caught in between the spring and the tang. Also probably coincidence with the drop. I’ve had it happen before. You just have to try and flush it out, either oil or compressed air. Try opening it part way spraying WD40 into the tang area, close it and wipe clean. Repeat. Try different blade positions if necessary. Toothpick can be helpful too. One time it was just a whisker from one of the dogs that required tweezers but it had the blade almost not moveable! Funny how most of the time you can get a knife covered in mud, woodchips, drop in crud and it still functions flawlessly. Then one time it’s the tiniest piece of something f*#@$ it all up!
I thought I'd report back since you were the one that helped me along, well after all else failed I did like you suggested and flushed it out with WD40. So much so I think it'll smell like it for weeks, haha. It did work to an extent, 80% of the action came back, but it's still not quite as smooth as the secondary blade(and the way the primary started).
It's a user I'm plenty fine with that. I may have found the culprit, though. It seems there is a spot on the side of the liner that has a cut in it, not very long or deep, but I can run my fingernail over it. I think what's happening is the blade rides over that and it scraps the side the blade, down where the markings/tang are. I'm a novice to these types of knives, so it very well could be something that forms over time, or it just happened to this. Either way it should even out over time which is fine by me, but thanks for the suggestion! I think a lot of grim will get caught by that little nick so I'll have to keep it oiled and clean until it flattens itself out.