Tracking force/weight  --  Violent oscillations of the groove walls tend to throw the stylus out, so downward force is required to retain it. This must overcome the maximum acceleration (1000 g) of the stylus mass multiplied by a factor of 1.4 due to the 45 dedgree groove wall angle. So for a mass of 0.5 mg, a force of 0.5 x 1000 x 1.4 = 0.7 g is needed to equal the stylus force. As this must be overcome with a safety margin, plus allowance for mechanical resistance, arm friction and side-thrust, it must be multiplied further. A factor of x2 would be appropriate. Excessive weight causes wear on the groove walls, but insufficient weight is worse as the stylus can lose contact then scrape the wall when it re-connects. Weight should therefore be adjusted toward the upper limit of the maker' s specified range, but should not be exceeded.