Gerry recently changed out the relays on his v3 µBitX. He had trouble getting the wick to remove all the solder, no matter what iron he tried and how much flux he used. So he tried another method.
There are a number of low-temperature solder products, the most famous/common, being ChipQuik. These are basically an alloy that includes indium or gallium. When added to a solder joint, this drastically lowers the melting point. You can melt the solder at each leg of a device, and by the time you have gotten to the last leg, the first will still not have set, making it easy to pull free the device. The risk to both the device and the circuit board will be greatly reduced. If anyone is having difficulty, or is apprehensive about replacing the relays, this represents a good approach.