Email Wacom would be the easy answer I guess...
Try this - see if you have any friends/local people who have a Graphire3 or 4 (yours is a Graphire2) and see if their pens work with yours.
If you can find someone LOCAL who sells parts - just the PEN - than get a new either Intuos or Graphire pen and see if it works - if it doesn't return it - or sell it on ebay if they won't take it back.

Can't find any listings for a new penfor a Graphire2 basically. Good luck!
-Lew ;-)