I just built a 1/10 scale buggy with Savox 1258tg servo. Installation went as planned and I followed all directions. This seems like a good servo except this...........With the buggy on, transmitter on and transmitter controls at neutral, the servo jerks back and forth about 10 degrees left to right over and over. Its acting like it is receiving constant commands to go back and forth but the transmitter is in neutral wheel position. I've tried adjusting trim and other transmitter settings but no help. I will note that the servo ONLY jerks when the transmitter is ON. I have a Spektrum DX3C radio.
Any advise?

Thanks, Rick