Hi, have you checked to see if the transmitter is transmitting in the correct fashion for the receivers?? I.E. PCM, PPM, positive or negative shift?? also, might seem like a silly question, but are the Rx's on the same Frequency as the Tx?? sometimes, even if some of these things are wrong, the Servos will get a "Bump" just from the act of turning on the Rx. or even from turning on the Tx while the Rx is on, even if it is transmitting on a different freq, Modulation, or Shift.