when i first started flying helis I had the same problem--I checked and re-checked everything until one of the experienced guys said its probably the training gear--I finally got up enough nerve to take off the training gear and she was smooth--the heli was also the nexus--also try adjusting your headspeed--sometimes that helps--remember the downwash of the rotor is is blowing air down on the training gear and it starts to vibarate then the whole heli starts to shake..Get an experienced flyer to try it with the training gear off and see what happens....good luck....joe