I wouldn't have any problems reusing servos or batteries. I can bench test them well enough to know if they are going to work right. I will not use a crashed receiver, though. We had a guy at my old club that crashed his bipe right into the pits. His receiver stopped taking inputs when he was turning to fly over the runway. He told us later that the receiver in that plane was from once he had crashed before. I just wouldn't trust it. I've crashed two planes possibly due to receiver malfunctions, and neither of those receivers had crashed before. You could send the receivers back to the manufacturer, but I think I would just replace them. Why take the chance.