Hello Scott,
Just finished balancing my blades a couple of days ago, and finally, yesterday -- we had enough wind to turn the mill !!
SUCCESS, it spun, with no noise or vibration !!!
The first time I did the balance, it was hung horizontally by a string, in the center hole -- then used a small bubble level on the hub...
I have used this method many times before, but it didn,t work on this prop -- So, I built a plate, that bolted to the wall, with two very small precission bearings in it, and an adapter, that fit the prop hub -- all a pain and very time consuming!
I used the flat weights with the sticky backs, they use to balance mag rims on cars -- they come in a strip about 1/2" wide, and you can nip them off in 1/4 ounce sections -- I tape them in place ,to test for balance -- when that is accomplished, I mark the spot on the back side of the blade, drill a small hole in the weight, strip off the tape from the stickey back of the weight, and stick it to the blade -- then a 1/2" long "tiny" screw, thru the hole, into the blade -- this is just extra security, should the sticky tape give up !!
The screw I use, is brass, and countersunk -- it is very nearly, the same weight as the lead removed for the hole and countersink..
In your case, if your mill turns freely, you can do this "in Place", but my mill, "cogs" badly, so I could not do it in place ...
Knowing how high your tower is, it looks dangerous, and scary -- trying to do it up there !! But, if you pre drill the weight, and have a couple extra screws (to drop!) It could be done...
I put that screw, toward the leading edge, with the weights trailing behind ,on the "back" side and about half way out toward the tips -- the further out, the less weight required, but the tip is to thin to be running screws into and more affected by aerodynamics !!
I hope this helps you, be carefull and best of luck, Bill H.....