Before you start sanding and grinding and cutting and lubricating and all that other jazz, try this very simple fix first:

Vacuum the inside of the socket, and wipe down the tube with a clean dry rag.

It's rather shocking how even a TINY amount of "stuff" in there will make a wing tube nearly impossible to install/remove. I've seen simply CLEANING the inside of the socket and tube work on a number of airplanes.