What is probably happening is the swashplate is bottom-ing out on the lower holders and after
it can't go anywhere it has no choice but to seperate when the servos keep pushing on it.
It also happens when you move your linkages out to the 4th hole on the servo arm.


Also, you could have placed the lower aluminum blade holders down to close to the swash plate,
the lower holder is acually 2 pieces. The bottom half is cut all the way down so you can move it
up and down with the top part of the lower head.

Anyway, take the set screws out of the lower head and make sure that the TOP set screws of the lower
blade holder line up with the holes in the outer shaft. Tigten them and then push up on the lower
section of the blade holders and then tighten them up.

Then work your servos and see if it still is happening or not, before you take it up again .