Every time I've had an extruder "skip", it was actually because some condition was causing excessive back-pressure. Either the hot end isn't hot enough, the nozzle is too close to the bed, or something has clogged the nozzle.
If there is a "skipping" noise, then this is almost certainly the problem. When a stepper can not advance, the magnetic field will continue to "step". After the rotor is behind the steps by 180 degrees of field phase (which might be only a fraction of a degree os stepper motor shaft rotation), the rotor will snap back to re-align with the magnetic field. The sudden movement of the rotor and the release of compression on the filament often makes a loud clicking or thumping noise. If you can see the gear, it will jump backward and then rotate slowly forward before jumping backward again.
To see if it is the drivers, try extruding with no filament, or if you can, try moving filament through the extruder. If it doesn't move at all, or doesn't move under light drag, it may be the driver, the wiring, or perhaps the motor.