Well if you lost you analog nub or want to add a tiny aspect of pride to your psp then gather up:
First, take off the analog nub then you will see the a tiny stub with a hole in the middle.
Second, cut the brass part of the tack off leaving some so that the tack is secure in the hole.
Last, stick the stem of the tack into the hole on the analog module.
DONE! Cheap new analog nub