The J and S shape tonearms (need to) use the so called ''lateral
balance'' weight in order to get equal pressure on both horizontal
bearings. The J kind is difficult to balance while the S can be
balanced by lifting up the front side of the TT and then moving the
later weight till the arm reach equilibrium postion. From this it
follows (?) that stright tonearms can't be in equilibrium position
because one side of the bearings get more pressure than the
other.