PS3 pad dropping diagonal inputs. Any way to fix this?

I’ve had my PS3 pad for a while and it’s broken in the way I like it, but lately I’ve been having an issue with dropped diagonal inputs when doing fireball motions. What might cause this and is there any way to open it up and fix the problem?

There are a lot of youtube vids on how to open up PS3 (and PS2, which is easier) pads. The issue might be that underneath the plastic d-pad, is a little cross-shaped plastic piece that goes in between the four cardinal directions. So if the d-pad was a +, than that piece is an x, which I assume let’s the d-pad register diagonals without having to really press down on forward and down. That little piece might be broken, but the piece is the same in PS2 and PS3 (and I assume, PS1) pads. So you could probably just open up another pad that you’re not using, take the piece from it, and replace the one in your favorite pad.