This is, alas, a cheap knife. Now it’s doing cheap knife things. I mirror @[email protected]’s prediction that the part getting out of place and causing you trouble is the spring for this knife’s spring assist mechanism. It’s supposed to have a hook bent into it that rides in a hole in the blade’s heel. The hook may have snapped off, or your main pivot screw may have backed out to the extent that there’s now too much of a gap to prevent the spring from working its way out of place. Based on the amount of gap I can see I theorize it’s the latter.

You’ll probably find something rather like this lurking beneath one of the scales:

How that goes in is the hook on the end goes in the hole in the blade, and the wiggly part of the spring rests flat inside the pocket carved out for it on the back side of the handle scale. There will be one (or most likely, two) positions in the blade’s rotation where the spring is completely slack and won’t be under tension against either the edges of its pocket or the barrel of the pivot screw, and keeping the blade there when you reassemble the knife will make your life a lot easier.

It’s unlikely any screw in this knife has an anti-rotation flat on it, especially the main pivot screw, so you’re undoubtedly going to need to stick a screwdriver in both sides at once to get any of them undone. Cheap screws are likely to strip when met with cheap screwdrivers, or at least screwdriver tips. I prefer Wiha screwdriver bits since they seem to hold up the longest and enact the least amount of violence on cheese soft Chinese screw heads. The body screws are probably threadlockered as well, and you can encourage them to let go by pressing the tip of a hot soldering iron against them for thirty seconds or so. I’d advise against bringing a heat gun or torch anywhere near it.

T6 Torx and T8 Torx are the two sizes you’ll need most often for taking apart knives. You can buy these online individually for a buck or two a piece of you don’t want to shell out for a full set.

I’d categorize this as a learning experience: This is an inexpensive knife that’s not exactly manufactured to a high degree of quality or care. But the way it comes apart and goes together is indicative of most modern folders which includes better, higher quality knives you might own in the future. If you ever have to delve into one of those, the skills and construction methods you learned from this one will be useful.