Hi Eric,
I restored a 'Benson' type gyroglider a few years ago, it's a one or two seat autogyro, to be towed along a long runway behind a car, the amount of height realised depends upon the length of tow rope.
My efforts in the restoration involved redesigning the joystick control system, and the 'rotorhead' assembly (hence my nick), which involved making up an all sealed ballrace type of 'gimbal head'.
I'm afraid it's now dismantled, and stored on the shop materials racking, the only part of the rotorhead assembly left, is the rotorblade hub bar.
Chris