I can't think of anything which would create confusion between fuel and hydraulics; especially with excessive vibrations during run-up. I suppose "preparatory to take-off" could mean anything from initial start-up to before take-off checks. The AFCS hydraulics are an obvious culprit with vibes since there could be adverse feedback, air in the system, or any number of other problems. A fuel blockage though should really only starve an engine and cause it to run weak or shut down completely (assuming it is beyond the cross valve).
I think I would be more worried about imbalances in the driveshafts or rotors.
I'm with Whirlygig, take this with a grain of salt!