RE: TIght Wing Tube
How old is the plane?? How often used is more the question. I have one with a tight wing tube. I ran steel wool attached to a long brill bit attached to my drill and cleaned out all the old gunk, there was a lot. Then I cleaned off the wing tube and used some IVORY soap on it for a lube. That loosened it up enough to slide without too much force. If it's a new plane then as LNEW mentioned, there may be a slight alignment problem?