If I were you, I'd just find the chain-rings for the crank you already have. As long as it's working out for you and you like it, no reason to spend the money and replace a perfectly good crank. Have you cleaned the current chain-rings well? A grease/grit build-up will promote chain suck. Unfortunately I can't tell you how to determine what rings are for your crank. You should be able to just buy them based on the BCD and if they're made for 4/5 bolt cranks.