These days there are several sources on Ebay which furnish complete kits for specifically repairing this model of iMac. They are presorted, and you don't have to worry about the ratings, voltages and physical size being correct. At around $20+shipping, this is by far the easiest method to acquire these caps. I have resurrected 3 iMac G5s with Ebay cap kits. Note that capacitors can fail without showing visible signs such as leakage and bulging.