Both the spring and the counterbalanced arms often have some mechanism by which the tracking weight of the stylus can be increased or decreased. But none of these measurements will do you much good unless you know the actual weight of the pickup you are using and the weight of the pickup for which this particular arm was designed. If many of your records are warped, certain precautions are indicated. The GE Baton arm, the Pickering, the Garrard, the Shure and the Weathers arms are engineered to operate well on a warped disc. The functioning of the pickup, however, is more important than the perfection of the arm.
Most pickups operate best in arms made by the same manufacturer.
In some cases no other arm will do. The Ferranti, Leak, Shure and Weathers pickups will hardly work at all in another maker's arm. With the GE and Fairchild pickups you have a choice of arms, because these are the most popular in the business and every arm is more or less prepared to bold them. It will not track quite so well as the separate arms, and the turntable is not so well weighted for the avoidance of wow and flutter. But you'll have to be pretty good to catch the difference, and the price is definitely right.