Quick solution: E6000 adhesive.

E6000 Glue on Amazon

Easy to get at hardware stores too.

  • Put a drop of glue in the hole where the alignment pin goes. Too much glue will just overflow and make a mess.
  • Press the pin back into its place as far as it will go. 
  • Have it held in place (clamp, etc) for 24 hours to cure.