Not an unusual size. The stepper driver can still force 2 amps through it, even with many ohms of internal/external wire resistance.
It -would- take the current it needs, if only you supplied the motor with it's normal working voltage, which may only be about 2Vdc. I'll bet though that your controller is being fed from something like a
24-40Vdc supply. The idea is for the drive PCB to force a fixed (usually marked on nameplate), controlled current through the motor winding, that will not be affected by connecting wire resistances, or the evil, increasing coil impedance which is a big problem at faster and faster stepping rates. One problem is, that as the driver PCB has so much voltage headroom to play with, a careless setting of the current adjust pot will happily force say 2 Amps through a 1/4 amp motor. A minute later and the motor is toast. The driver PCB doesn't mind what's on the end of it's wires.
Yes. Set the current lower. You can always wind it up later if more performance is needed. I'd start at maybe 1/2 amp (or less) and see how it goes. At continuous full rated current, the motors bodies can run -very- hot. This is most noticeable with the motors stopped or doing little work. Because of this waste of power some drive boards allow entering a low-current/sleep mode, if no steps have been sent for a couple of seconds. This can be about 10%-50% of nominal current.
Thanks to you both for your replies. I can certainly confirm that last bit. I had to go out in a hurry and left the whole lot powered up for about three hours and the motors were very hot when I got back. I'm now a lot more careful about turning everything off. I'll also wind the current down and see how I get on. Thanks again