If your spacebar is having the same problems as mine did then it's an easy fix.
Gently, gently, gently pull up the bottom edge (the one closest to you) and pop they keycap off. Clean out any dust you may find. Then look at the keycap. Do all the clips have two prongs (to grab the metal bars which hold it in place and give it stability)? If no, you'll have to get a replacement keycap.
In my case, I just made sure that the long metal bar found all its prongs, and then clipped the other side over the short bars (three under my spacebar keycap).
Working perfectly now, and it's rigid again, so I can hit the spacebar anywhere and it works.