I am going to go out on a limb for this one, but here it goes.
here is what I origionally was trying to do (BEFORE I drilled the wrong hole):
Method 1:
Basically take the controller apart (I assumed you already did). Look at the layour of the controller's pick. If you have a metal "tab" on one side, get some sheet metal, do some "acurate cutting" OF the tab (in otherwords, a duplicate), then try to see if you can insert it on the other side.
Now be careful when doing tihs, drill a whole but MAKE SURE you DO NOT, I REPEAT DO NOT cut on a "circuit lining" that represents the pic's up/down function, otherwise you will be fucked, try to go above or better yet, use crazy glue.
You can also do the same thing I mentioned above, but use really tiny springes, you can get them at lowes/home depot, but be sure to bring your pick with you so you can have an acurate size. After you done all of that, put it back together carefully

.
Method 2:
If you have a broken-down psx controller, if you take it apart, you will notice some square-rubber squares, these are called "gums", try replacing the gums on gf controller and put it all back together.
I hope that helps.
See yaz bye.