i have a couple of spare for my own KA booms. i think i got them from surf sail australia a few years back.
i get a lot of spares from them so may be worth a try.
i started storing all my booms with the clips out because they would blow out from rust. seems to have increased life span.
www.surfsailaustralia.com.au/product/surf-sail-australia-boom-extension-clip-blp2003#surf-sail-clothing-hardware
this might be them. ?
