Rabco

   Pretty much the invention of the linear tracking arm as we know it, this "clunker" is still coveted by many today. Powered by a C cell battery, a ball chain moves the arm across a channel with rollers determined by a metal "whisker" that makes contact as the arm is drawn in.These seem to hold up forever, with minor maintenance.

 I still have one of these, not really sure what to do with it.

 Harmon Kardon bought the rights to it a few years later and used it on some integrated 'tables, the ST-7 being the most famous.