Sidebar - or when checking the buggy I found a rattling drivers seat, and took it apart...well enough so I could take the seat attach bolts off and see whats up with them. The passenger seat was still rock solid.
The fastener on the rear inside part track was loose, how'd that happen?
Not correct tighten to torque specs by the mechanic who assembled my go kart?
I cleaned everything off, applied blue loctite, and re-assembled back torquing correctly.
.
Now everything works better, slides back/forth good, and no rattles.