Awesome that it’s coming apart well. The Zerk (grease) fittings seen on some of the moving parts certainly helped as there was no doubt a layer of old grease in there keeping moisture and corrosion out.
I really like the kart, even the “banana brakes”. We hear from 350lbs dudes on fun karts with only one brake and they’re wondering why it won’t stop very well. Your hand-me-down kart has two brakes at least. The underside and the wishbone thing reminds me of the bottom of a Model T.