Hi,
The needles screw in brass tubes that protrude from the carburettor. Each of those has an hex-shaped portion which allows the tube to be tightened so the needle won’t migrate during operation or loosened so as to still permit the needle adjustment. Just don’t play too much with those as the packing could leak if disturbed too much.
There are no old outboards, just machines so well built, they have outlasted their owners !
