There is only one balance point- water level. I had this crazy two balance points as well. In most cases the vertical bearing races are dirty,stuck, damaged or overtightened.
It took me a while to figure out why I still had a "high and low" on a thoroughly cleaned set of bearings with perfectly set bearing play.
Turns out the "Magnetic" part of the cart did its job-- rather too well--.
The cart/arm, if over compensated by the c weight, will of course raise the cart. As soon as the c weight/cart neared water level, the cart's magnet would pull the arm to chassis and thereby creating what would seem a low balance. Getting fed up with this nonsense I removed the (1219) arm from the unit and balanced it off chassis:
To sum up,
a. check the bearings if they are clean an the balls rotate freely,
b. check the play on the bearings
c. make sure the tracking dial is set properly at zero/line on arm
d. make sure the spring is set properly inside the dial housing.
e. make sure that the arm is (water-level) balanced
In case of magnetic attraction, balance as close as possible, before arm gets pulled.
Once these precautions are taken care of, these dials are incredibly accurate from the 1009 onwards:
Klaus Adlhoch, fmr. Assistant Service Manager,
Noresco -N.Q.I.-Dual of Canada,
Area of expertise: Tech Training and Consumer Service P.R.
Associated with Dual till Thompson era.
Favorite Duals: TG 12a, 1009, 721.