Sorry if this has been beat to death elsewhere. If so couldn't find it.
None of my Slingys show any signs of any finish applied to the interiors. I'm getting them back to top and bottom heads. I can't see how any fluid could get spilled inside. I see posts about Feed/Wax etc. Wouldn't that alter the tone?
I'm leaving them as is unless a better approach surfaces.
Thanks!
Creighton