That metal part sticking out is really fragile. Don't touch it if you ever take your switches apart. If you accidentally bent it somehow, you can rebend it back to original shape, although getting exact is very hard and you depend on a little bit of luck. Even if it looks like how it is before, the middle part that actually make the contact might not be exact. This will cause it to actuate a tad before or after where it's suppose to, and if it's too far off, it won't actuate at all.
how did you bend that spacebar switch in the first place?