Sean,
There is a better description of the mechanism in Jason Gold's review of the ST-7 at Audio Review (of all places!):
http://www.audioreview.com/TurnTables/Harman,Kardon,RABCO,ST-7/PRD_121324_1597crx.aspx
Because the rotating tracking arm is coupled to the rotation at the platter spindle, I don't think the HK versions of the Rabco arm can be fitted readily to other turntables.
I thought the HK was a pretty good-sounding turntable, but I don't know how it would compare to today's "meat and potatoes", like Regas.
There is a better description of the mechanism in Jason Gold's review of the ST-7 at Audio Review (of all places!):
http://www.audioreview.com/TurnTables/Harman,Kardon,RABCO,ST-7/PRD_121324_1597crx.aspx
Because the rotating tracking arm is coupled to the rotation at the platter spindle, I don't think the HK versions of the Rabco arm can be fitted readily to other turntables.
I thought the HK was a pretty good-sounding turntable, but I don't know how it would compare to today's "meat and potatoes", like Regas.