I decided to act upon excellent advice given to me by Craig Reinbrecht. Both Craig and Mike Joyce had collaborated on a way of decreasing the noise of the hankscraft motor used to spin the crown and extend its life. This involved eliminating all friction and pressure on the motor. In previous designs for the brain assemly, the entire weight of the crown rests on the shaft of the motor. This led to early demise of the motor and a great deal of noise.

The key to reducing friction, Craig explained to me, was to install bearings in strategic places in the brain. The second component of this method is to attach the drive shaft extension to the shaft of the motor in a way that prevents the motor from any contact with the drive shaft. In the photo above you can see the thrust bearing in the top plate of the brain. The drive shaft runs through this bearing, which prevents wobble.

I also elevated the thrust bearing inside the brain using a couple of steel washers. I did this so that I could better see the light rods as they engaged with the brain cam.

 
The weight of the crown flows down the drive shaft and is arrested by the brain cam, which is secured to the shaft with a set screw. The weight is then transfered through the brain cam to the thrust bearing and down to the bottom plate of the brain. This method eliminates all weight below the brain, enabling the drive shaft to be practically weightless immediately above the motor.

Additionally, the drive shaft is only loosely connected to the motor. I drilled a hole through the shaft of the motor and a corresponding hole through the aluminum tube that I am using for the drive shaft. With the holes lined up, a thin length of wire is inserted and wrapped around the shaft.

 
It is a beautiful and simple system. Thanks to Craig Reinbrecht and Mike Joyce for inventing it!
 

Miniature Precision SS Ball Bearing - ABEC-5 Flanged Shielded, .25" ID, .375" OD, .125" Width	McMaster Carr Part Number 57155K153	$ 9.05 Each
Economy Ball Thrust Bearing Stainless Steel, For 1/4" Shaft Diameter, 9/16" OD	McMaster Carr Part Number 6655K33	$ 2.20 Each
Drive shaft: K & S. Engineering Chicago, IL. 1/4 x 035 Round Aluminum (6061-T6) Stock No. 3031	Ace Hardware	$1.89 for a 12-inch tube
Hankscraft motor	bought second hand