I found with the Ventus and Nimbus it is good to clean the pins on the end of each spar root and wing root should be cleaned with 00 steel wool every few years and then lubed carefully. The spherical bearings on the fuselage and on the wing roots should be cleaned until they move freely. They can be rotated and removed if installed correctly (incorrectly and they go into the tubes). Q-tips and solvent will help free then up.

I have found many ships have never been cleaned in years.

Usually the tightness for the last 1/4 to 1/2 inch are from lack of cleaning as long as the flaps, spoilers and dump valves are set correctly.