Geor, they may have springs but that cannot be considered an adequate ground. The motor must have a wire that does the job, so plinth, motor, platter bearing and arm have the same ground.
The motor may not be shielded, but if you ground it that may not be important! Certainly an ungrounded, unshielded motor *will* be a problem for an unshielded moving magnet cartridge!! So get it grounded right and let's see how it works.
The motor may not be shielded, but if you ground it that may not be important! Certainly an ungrounded, unshielded motor *will* be a problem for an unshielded moving magnet cartridge!! So get it grounded right and let's see how it works.