Frank,

You mentioned that you are using PCM. This type of transmitter uses CRC, or Cyclic Redundancy Checks.
While not going into the actual transmition and reception, i'll try to explain what can and cannot happen.

See, the transmition of signal from the transmitter to the receiver is coded, and if part of the signal is garbled, or missing, the receiver ignores that part of the signal, leaving the servo in the last known position. This is why having the antennas too close will NOT affect a PCM radio.

Low batteries can make the radios do very strange things.
Chatter is just one of them.
Inteference is ignored by the PCM system, so servo chatter/jitter is not caused by interference, unless it is another PCM radio on the same frequency nearby.
Flourescent lights will not affect a PCM radio.

Bad POTs in the transmitter, and bad POTs in the servos can cause chatter, but unless the transmitter was used in the rain, it is not likely that all channels would be affected equally.
A bad receiver can cause chatter in all servos.

I would recommend charging the batteries overnight and recheck it.

Let us know if that fixes it.

Here is a link with information on PCM vs. PPM if you are interested.
http://www.aerodesign.de/peter/2000/...M_PPM_eng.html

Bob