Help in understanding a particular motor

Hello.
I’m gutting a real aicraft instrument (an altimeter) in order to hook it up to a flight simulator.
I know I’ll end up gutting it for good and install steppers and servos I can easily control (already done).

BUT

I’ve did my reading, here’s a couple of links I’ve went through:

https://forum.sparkfun.com/viewtopic.php?f=14&t=34876
http://www.simpits.org/forum/index.php?t=msg&goto=3857&S=92baad68439590973ee8ee6e5727b19f

Fact is these instruments are run by synchros, the signal came from an iar data computer and it ran at 115V 400hz. I do not intend to replicate that kind of signal/control system.

BUT:

Inside the instrument there are two “motors”, both are connected (via gearing) to the dial output shaft.I guess one is a synchro receiver and the other should be a resolver.

I know I won’t be able to use them, but I got curious and tried hooking them up to see what would happen. You can see it in the pictures, it’s the “bare” one (the other has still things around it). The output shaft is not actually fixed but has a “bell” that goes inside the motor body.
Now, I know its gotta be unhortodox but I wired it to an ULN2003A that came with cheap steppers,gave it 12V (5v did not work) and, using AccelStepper library,with microstepping, I got it to run. Meaning:
-it does move in both directions
-the movement it does is proportional (but not linear!) to the number of steps I command it to advance (e.g if I command 500 steps the dial goes 180 degrees, but if I command 1000 it does more than 360, sort of exponential)
-if I command 100 (or 1000, or 10000) steps forward, wait for it to stop, then command 100 steps back, it does NOT return to the starting position, but a little less (and that less is proportional to how many steps I gave it).
-if I set the speed to over a certain amount, the number of degrees per “step” gets greater (basically over 300, i command some steps and it starts running like a thief).

If I hook the other of the two “motors” i just get a buzz but no movements.

Soo, my question is, do you think I might it to behave like a stepper, or is it a lost cause, and, maybe, I can treat it like a DC motor (and add somesort of feedback loop)?
Has anybody (apart for the few threads I linked) had any luck with similar kinds of motors?

Thanks and best regards!