doesnt Redcat have a rebuild kit?
Those Shocks are SUPPOSED to be rebuidalble, so they MUST have a kit, or at least parts.....

I bet you could find some parts, (o-rings ,shafts. plungers, oil) on TOWER Hobbies. Many Shocks from different MFG's are very similar.
The problem is choosing WHICH parts...lol....You might have to spend some money before you develope a list of interchangeable parts.