How old are they?
I spray a (very) small amount of my gun lube into each of my magazines after each use. It keeps them feeding properly. Unfortunately I can't offer too much help with hi-caps. I've never had much luck with them in the past (too many broke).
Against popular belief, some hi-caps can be over-wound, causing either internals to break or at least cause minor damage to them which can hurt the feeding process. Do you typically stop winding when you hear the clicking?