Help figuring out stepper motor

[Silenus]

I have a stepper motor I scrapped from a printer and I am trying to figure out how to run it. It has 5 wires so my first guess is that it is unipolar with a common tap on both coils, this is confirmed from resistivity tests. Now in the datasheet it says to drive it 2-2 phase excitation (bipolar driving). Does that mean I can't drive it as a unipolar system with the centre tap connected to Vcc and the 4 coils going through a BJT to ground? I've hooked it up as a unipolar system with 1-1 phase excitation but the motor just makes jittering noises with no visible movement no matter which combination I have the wires in. Any advice?

[Rerouter]

from the center wire, all 4 others should measure the same resistance, or very close to, he will be connected to supply, the other 4 will be switched low in sequence, should be the same as a 6 wire unipolar,

it is likely that it requires overlapping steps rather than just 1 on at a time, e.g. A, AB, B, BC, C, CD, D, DA.

[Andy Watson]

With four wires and a common you can usually choose either unipolar or bipolar drive.

Down at the  bottom of this page is a link to a pdf of "Product Information", it gives the wiring diagram and shows both unipolar and bipolar configurations.
http://www.mitsumi.co.jp/latest/Catalog/compo/motor/index_e.html

What voltage are you using? The data sheet specifies 21 to 26V. Your description suggests that there might not be enough drive.

[Silenus]

I'm giving it 24 V and I just programmed in a 2-2 phase excitation, now the motor is turning in time with the pulses but it was drawing an amp and started getting warm so I shut it off. Is that sort of current and temperature normal?