while reprograming a group of 15 units. one would not read/write-communication error. only variable was radio-cord in same position. tried usual messing with plug-twisting/push/pull etc. no luck. put small squirt of electronic contact cleaner followed by brief air burst, into socket holes. unit now read/write with no problem suspect possibe corrosion. unit had been in use for about 6 months

73, jimstuder kf8sj