Spacebar Broken 3 Times

This is the 3rd spacebar I have ordered. I realize there is that metal thing and where it goes in the spacebar. I checked as before to see that the metal thing was secure in the plastic holders. It was (as I thought before), and I proceeded carefully to put the spacebar back in (with the metal thing towards the back forming an upside down U). When I did, once again, the metal piece dislodged itself from inside the keyboard and I put it back, however, it's not firmy in the grooves as it was. It works, but feels different than all my other keys and sometimes, and it is not working smoothly. So now I have 3 spacebars with the metal bar. Previously, I taped it so it would not move and it worked, just not perfectly.