ORIGINAL: mnrcaerobat
I'm running twin aileron servos in a bigger plane. There are four servos total. Two on each aileron. I have one set of servos plugged into a y and then running into separate channels in my receiver. The right aileron works great, but the left pair will not work together. I have tried both servos and they work by themselves, but once I put them together they chatter and don't center or start by themselves. I changed the extension on the outermost servo, and even tried a different y. I can't get it to work. The servos are all hitec hs-5645mg, and are all centering individually, and are rigged identical.
Is one of the servos bad?
Get rid of the Y Harnesses
I have rxperienced problems such as you have seen and replacing the Ybwith a good quality 20ga Y helped. I use JR Matchboxs or Furtaba Servo Sync, instead. If your Tx has enough channels, use Channel Mixing.
A Smartfly device is also an alternative. Never use a Reversing Y..