The quest for obtaining servo-armor is given by the soldier after on the -3rd floor of Magellan - he stands next to two empty armor - from the elevator straight ahead and to the right around the first corner. And then there are random events on the journey - you may meet a dude stuck in a servo. And when you get him out of it, the empty Servo Armor will become ownerless and you can take it for yourself.
Massaraksh
This is not a random event, but a very specific loca - "The foot of the dune" 3 squares to the north and 1 square to the east of the "Phalanx" base. There is a Mark 3 armor. But the quest with the starting upgradable armor starts not at -3rd, but on the "Warehouse and garage" floor. We must go to the garage door and let the man in. After that, he will move to the garrison floor and you can take the quest.