The 1946 Berkshire and turbine motors did not have ball bearings. I believe it is because they didn't need them. These motors had spur gears at the end of the armature, and didn't have any significant thrusting force for ball bearings to address.
When they went to worm drive in 1947, the motors were subject to significant thrusting force, and ball bearings were added.
The first motors had loose ball bearings. Later the ball bearings came mounted in a ring. I am not certain when they changed(probably 1950). I think 736 motors have the bearing rings.
The 1949 622 motor also had loose ball bearings. The page listed on Olsens web site gives the number of ball bearings as nine. On all these motors, I usually put in as many as will fit without bunching.
