Square 1 Help? Corner piece pop!

[vancuber]

So I ordered my mf8 square-1 and I brought it to school. I let people try it and then some guy forcefully tried to turn it when it obviously could not, thus popping the corner piece. It's darn near impossible to get back in. Any suggestions?

 

[gundamslicer]

Put in the giant pieces+ 3 small then turn vertical face 20-40 degrees and force it in