BBL,
Surefire is great when it comes to replacing a defective or broken part. However, some parts are just not avaiable from them as "spare parts". Over the last year or so, I have managed to scrounge almost everything that I needed but I had to work at it. I also had to buy additional flashlights just for parts. Some of the distributors like Dan @ "Tacticalwarehouse.com" or Wayne @ "Lagger-pro.com" are a great help and source.
Hope this helps.