In photo 1 below, the red arrow points to the phenolic block which supports the right side yoke shaft, just aft of the panel.  It's mounted to the steel tubing that also holds the instrument panel itself.  Photo 2 is a shot from many moons ago during an avionics upgrade, which shows the block a little more clearly (in the red circle). Periodically when moving the elevator during preflight inspection, the yoke shaft "chatters" in this block.  It's been doing so for a couple of years now.  Wh