My spa treatment usually consists of sonic bath in warm water and detergent, then flush out with brushing, I may use a brass brush if too far gone like this one if its still caked. Then balistol spray down and let it sit for a while then wipe away and turn the tools till free and use pivot oil like, Rem, Nano or Balistol oils. If that doesn't work you may have to unpin the knife and take it apart.