I have been balancing them on the heli and it seems to be ok. I don't have any balance vibrations.
First I set the blades a little stiff, but loose enough to spin out straight.
Then I spin it up until they are out and vibes are minimum.
Next spin down SLOWLY.
Loosen the motor and move the pinion off the main.
Turn the heli sideways and the heavy blade will fall.
It usually takes one or two 2 inch strips of scotch tape running with the chord of the blade and placed towards the tip.
Set your pinion back.
Done

And I will also do the paddles without the blades on first.
Pretty quick and easy. And I have sometimes found more effect from offset of the rotor head on the rotor head bearings. Look up under the head and you may see it. Not much can be done about that, except maybe balancing it on the heli.

SB