Got our second RCX 2. One is out of state from last septemer till late spring 2012 when we make trip to check it. From useing it 3 months seems all is good. The second one i inserted batteries and it would not register on handheld computer. Dinked with it and found the two contact points inside where the battery cartridge makes contact WERNT! Reached in with needlenose pliers and carefully pulled them out a little. All good for now. Could see this happening again with time.