Slimmy,
Keep the old one around so you know where to drill the new hole. It also is  
great to carry around in your pickup truck when you go into the bad part of  
town. :)
I keep my old one in my truck when I do roof inspections. I've only had to  
use it once, but it was very persuasive with the homeless drug addict I was  
threatening. He left without further incident.
 
Rummy