I think it's kinda funny this thread popped up again; I never did come back and update with what I found. After all the comments here and all my attempts with various things and stepping away from it for a bit since I wasn't getting anywhere, I went back to it one time for another look to see if I could tell which way the threads went. What I saw made me feel like such an idiot I had to walk away again: When I lifted up the mower deck and took a good look underneath at the bolts holding the cutting blades on, I couldn't see any threads at all. Because I was looking at the bolt head, not the nut. The bolts come up from the bottom, the nuts are on top. Freakin' dipwad. No idea if it's supposed to be that way on this model or if the last owner just put them in that way, but whatever. Haven't even bothered trying again since; probably will sometime this winter since other farm stuff will be slowing down a bit.