The robots can absolutely be configured without a break on all 6 axis, Hence the question in the controlled start prompt. On an Arcmate 100i you cant see the servos for J 4,5, and 6 without removing cover, but you should be able to see the brake cable connection for J1 if its present.
You are correct. I looked at the J1 servo and to my surprise there was only 2 connections into the motor. The other 100i we have has 3 connections on the J1. I had no idea they made 2 different variations robots. They are both from 1997, both 100i arcmates.
So basically here is what it is, these are the part/model #'s of the robots:
6 axis brakes: A05B-1210-B601
2 axis brakes: A05B-1210-B201
The 3rd number from the right I'm guessing signifies how much brake controls there are.