Its probably low head speed combined with bad tracking.
At hover pitch, about 6 degrees, I run my OS32 at 65% throttle to keep the head speed high. I also found that if the tracking wasn't correct, it would cause the shakes as you describe. Check the tracking just as the bird gets light on her feet not at zero pitch.
As for training gear, I never had the problem with the shakes, but I did have a problem with one of the legs swinging up into the rotor disk. DOHH! Those plastic balls go quite a distance when hit with a 200mph bat!