Well if it makes a scratching sound and sticks, it sounds like the motor is out of place, or that the the voice coil bobbin is out of original shape, or something is preventing it from moving freely. It could also be that the glue got hot enough to melt, and the voice coil undone.
What kind of power were you sending them? What are they rated?
When you press down, are you pressing directly in the center, or on the side?
Did you by chance happen to have any of the following happen:
Dropped it?
Bottomed it out bad?
Had it in a place where it could have accidently been pressed in really hard?
Had it in a posistion where dirt or something could have gotten down there?
Had an accidental quick short at amp, or cause speakers to pop loudly?
Also, look over the magnet. Does it seem to be out of shape at all (compare it to the other one)
Measure the resistence at the terminals again, and tell me what you came up with.
Do you have a warrenty?
Let me know those answers and we will go from there.