A volt meter is not really a good way to check these signals and they are pulses and do not deliver a constant voltage. Depending on the quality of the voltmeter and the duty cycle of the signal, you'll get anything from no voltage to a voltage reading much lower than the expected 5V. You really need to check the signals with an oscilloscope but that is beyond the capability of most hobby machinists and more expensive than it's worth.
So you made the right choice coming here for assistance. However, I'm not sure I understand the trouble. You said the machine cuts the sample files just fine which means the stepper motors are running and therefore your stepper drivers are getting the pulses. Could you explain a bit more what you're not seeing?
Stephen "Highspeed" Kruse