Rabco SL-8E Tone Arm

Everything still works, the lateral servo with chain drive, the lift/lower motor, rca to cartridge clip continuity etc. As I remember, it should not be used with a low output, low compliance moving coil, due to the low tonearm mass and servo servo motor noise, but worked fine with a high compliance, high output moving magnet. There is a sensitive adjustment for the fixed post which touches a first wire to turn on/off the motor for the lateral drive, and when when a rapid large displacement (runout gooves) occurs, it touches a second wire which activated the lift motor.

Oldears, you can eliminate the servo noise by updating the servo! Its not hard...

Depending on how well the servo is set up, it really can be a linear tracker, much more so than any of the air bearing arms I've seen. This is because its lateral and vertical tracking mass is the same. On an air bearing, the cartridge cantilever flexes somewhat, which can result in the tracking error being higher than a radial tracking arm.

So the Rabco was actually capable of the lowest tracking errors of any arm made.

The original servo essentially did not work though- it has to be rebuilt if you want the thing to work.

Is having equal vertical and lateral mass a part of the definition of a linear tracking tonearm? I would not think so. I guess you meant that it is one of the best SLs you've used, because of the low lateral mass, as opposed to any air-bearing SL tonearm which will have a high lateral mass. I have seen the issue of lateral mass argued both ways, high is good; high is bad. I have no dog in that fight. I think high vs low has to do with whether you use a high or low compliance cartridge, but could be wrong.