I recently installed a new motor in my Raptor (ThunderTiger 39). Now i seem to have intermittent interference. Throttle and pitch change and tail rotor behaves uncontrollable at times. I have since learned that loose parts can cause interference i.e. metal.
I just checked to be sure the motor is secure and found that I could tighten the mounting screws almost a 1/4 turn. Also I didn't have a rubber gasket between the muffler and the engine. Could that cause a problem, even if there is no noticeable play between the muffler and engine.

After tightening the engine mounts do you still have this problem?

Gonna find out this week. Just tightened them Tuesday evening. I will let you know.

You dont need any gasket between the muffler and engine and you surely don't want a rubber one.

If something isn't loose you have a bad bearing somewhere.

Sorry guys it took so long to respond. Since I talked to you last I have replaced the crystals (changed the channel from 16 to 59), and bonded the screw on the underside of the muffler to prevent it from vibrating. I ran about 3/4 of a tank through the heli and the tail shifted violently. I had an experienced pilot watching and he stated that the the swashplate tilted, indicating a glitch or interference.
What I failed to mention was that this heli had a modified antenna system (from the seller I bought it from). He had mounted a solid rubber type antenna inside the canopy and had shortened the antenna wire coming from the receiver and had soldered the two antennas together. The rubber antenna had a small white wire that was attached to the receiver antenna. I removed all this, mounted a new receiver and ran the antenna outside the canopy and through an antenna tube mounted to the skids. I flew today with two tanks of gas, no jitters or glitches.

Good show.