How do I find the inputs/outputs of an unlabeled transformer?
The yellow-green wire is certainly connected to the core the transformer, and is to be connected to the ground.

The blue and white seem to be the primary. I am surprised the resistance is exactly 0 ?

If you are sure the transformer corresponds to the one in the schematics, clearly the two red wires and the black one are connected in the same winding, and correspond to pins 6, 7, 8. I guess the two reds are 7 and 8 (order does not matter) and the black one is N° 6.

Of course, orange and gray correspond to 9 and 10 (order does not matter).

Are you sure the primary corresponds to the blue and white wires ? If you are, I think you can plug these two to a 100V AC source (don't forget the fuse). Then, with a voltmeter, you could check that the voltage between the 2 red wires is twice the voltage between one red and the black. If this is correct, my assumption about red/black wires is correct.

If you use a sensitive enough ohmmeter, you should get a small, but not null resistance between the different wires. I think the highest resistance should be between 9 and 10, then a little lower between 12 an 14 (primary). Resistance between 7 and 8 should be lower, and resistances between 6-7 and 6-8 should be half the resistance between 7 and 8.