Glitch
There could be several things. First, are you running a engine with ingnition (spark plug). If so, that could be a problem. If not, check for any metal to metal contact that might be loose. I have had glitches from a metal pushrod that ran from the engine to the servo. If you have a metal clevis on the metal rod, the engine vibration can cause glitches. Just change it out so that you dont have all metal ( plastic clevis). Let me know how it goes.
Larry