Did some checking at lunch. All extensions appear to have gold plated contacts. Load test on batteries - under a 1.2 Ohm load each battery delivered 4.96 amps or better. Measurements made with a Fluke 77III multimeter. With all other servos disconnected and the 8611 connected directly to the receiver (no extension) intermittent, violent twitching occurred sporadically. Receiver was the Futaba R127. These twitches are brief, certainly less than one second, probably less than one half second in duration. More and more, I am zeroing in on the 8611 as the source of the problem. I don't understand why I haven't seen it while using the R138, which was in the plane during the initial problem. Perhaps the PCM receiver is able to ignore the sporadic impulses most (but not all?) of the time.