I'm tipping perhaps , at least the 2 smallest cogs have wear ?, do they have little burs on the trailing edge?, if you put a new chain on , it will skip on those cogs under load !, you CAN get these cogs singularly (even shimano), if it is a shimano cass, knock out the 3 pins/rivets , get the replacement cogs and put cogs back on the freehub body one at a time like campy etc..
__________________
Velosophy#1: It is better to have a bicycle and no money , than money and no bicycle ! Velosophy # 2 : "Winning is simple, but not easy." #3: "Give a man a fish and he shall eat for a day , teach him how to fish and he will sit in a boat and drink beer all day"