Hi, sorry it took me so long to reply to your different responses.
So, I have checked the plastic insert and it is definitely not broken. I removed the lace to make sure the insert was intact with a lacing needle, and I'm sorry to say that there's nothing I can do about it. I even tried to push the thing a little on the side, but then the holes wouldn't correspond and I wouldn't be able to relace it. So I'm afraid that's all there's to it: this glove will hurt whatever I do!
I'll give it another shot, you never know...