You head to the next gun. As you make the transit, the firing pattern of the other turbolasers widens, then stops as they give up landing a lucky shot.
As you fly over the next gun, you see Imperial soldiers moving down the walkways to defend certain access points - you can make a guess they are moving to protect the repulsors, which gives you a pretty good indication which access points are for the power generator.
[Actions?]
There was talk of hitting the control room, or the power generator. Which one would you prefer?