This crib, The Graco model #4600 3 in 1 crib along with millions of other drop-side cribs has been recalled.
This may be part of why you are having trouble with the side-rails.
Here is the CPSP link reguarding this crib:
http://www.cpsc.gov/cpscpub/prerel/prhtml07/07307.html
According to the CPSP information the company appears to be out of business to some degree and are not providing repair kits.
If you know where you purchased the crib, check to see what their policy is reguarding recalled baby products.
We had purchased ours at walmart almost 8 years ago and were able to return it to another store in a different state for a full refund last summer. They did not need a reciept received, they just needed the manufacturer label on the part that the mattress lies on.
Because ours was older, the customer service clerk did have to work hard to find the crib in their system, but once she did, it was not problem at all.
