there was corrosion pitting on my 28 year old nacra on mast, boom etc. mainly under stainless fittings. used a dremel and little diamond ball heads, like a dentists, had to go quite deep until the white powder of alloy corrosion stopped coming out, left ugly deep holes

so filled the holes with several thick coats of anti-rust primer

sanded flat and painted over again with silver paint, to match alloy

then cut out some sticky aluminium tape to act as electrolytic barrier and re-riveted the stainless fittings back on with stainless rivets

not a textbook repair but total cost was about $10

3 years later, looks fine