Case can clean it up for you. If there's a charge they will notify you before starting work. Make sure you include written instructions along with the knife. Especially if the knife has sentimental value, make sure you tell them what you DON'T want done, like replacing the blade or some such.
Those knives are still in production so they should have all the parts if it needs parts replacement.
These are the instructions directly from Case:
"First...ALWAYS insure your package and ensure that it is in a suitable mailing/shipping package.
W.R. Case & Sons Cutlery Co.
Attn: Repair Center
50 Owens Way
Bradford, PA 16701
Second...ALWAYS be sure to write out what you want (i.e. repair, replacement, it is sentimental and you want the knife back, etc.) Never leave us to assume. We first Repair, then Replace with something comparable if it is covered under warranty. Be clear. (If it is sentimental and we do not have the parts to repair, you may want it back versus replaced.)"
Before you decide to pay to get it repaired, be aware that similar new knives run about $50 to $60 depending on where you buy it.