How to fix ni-cad rechargeable batteries.?

I have a small ryobi drill that uses the 12 volt type ryobi batteries. The batteries no longer hold a charge for very long, and wear out quickly after a full charge. Does anyone know how to fix these batteries? I see these $5.99 manuals on how to do this on the internet, but I was wondering if anyone has purchased one of those manuals, and if it worked for them.