Rick,
From my experience, I oil each shaft and set screw outside and inside. Age and electrolysis will cause parts to be stiff or seize. A drop of oil on a small screwdriver end is used to put on in areas where the oil can tip cannot reach. After enough time, there is little to no lubrication left making metal shafts stiff. I have even heated shafts with a soldering iron using the tip near where it is close to the heating element resting on the shaft long enough (a minute or more depending upon the shaft diameter and amount of heat desired to get it loose again) to get it hot enough to make the hard oil a liquid again or it will burn off then add new oil. That has worked to make a shaft that is very stiff to locked to easy to turn again. Shafts and collars that are Al can lock solid due to oxidation and must be replaced.
Mark
