The Garrard Zero 100 was an interesting engineering solution to tracking error. Unique implementation of the design.
The cartridge shell was pivoted, and an auxiliary rod was attached to the main bearing and the headshell pivot such that the rod would rotate the headshell to keep the cartridge parallel to the record groove.
This design required extra mass for the rod and extra pivots. I recall that the extra weight, the extra pivot friction, and the extra vibration from lack of system rigidity compromised the design's effectiveness.
While this unit may be a collector's item for its age and possible rarity, you may not be pleased with how it sounds. So are you a collector or a listener?