Damper plate, several threads with similar noises have led to this being the problem.
1983 MasterCraft Stars and Stripes
Cream/Red Metal Flake "Powerslot"
"The misery that is now upon us is but the passing of GREED-the bitterness of men who fear the way of human progress. The hate of all men will pass, and dictators die and the power they took from the people will return to the people and so long as men die Liberty will never perish."