Document feeder will not Operate (by 2 users)

I am having the same problem with this scanner.
Does the paper feed try tilt up? It does this to make the paper meed the rollers.
Are the rollers moving when you try to scan? You could look where the edge of the paper meets the feeder, with a flash light or good lighting you could see if the rollers are moving.
If not, and the belts for those rollers are on track. Remove the upper back cover. This only takes 2 screws.
Once removed, you can tell the scanner to scan again, and see what part is not moving.
The stepper motor engages, and spring moves, then another stepper motor engages and clutch should simultaneously move.
More often than not, the clutch might have gone bad.
I hope this info helps you trouble shoot your problem.
With my scanner, I need to replace the clutch.