Here in NY, usually during the last week of the season, I have similar results. If you don't hear any gobbles in the early morning, try to be in an area that you have seen and taken birds before, preferably near a roost site. Plan on staying all morning, so get a comfy seat. I give out a few calls and wait 15-20 minutes. Go softly with the calling as well. By this time of the season, they have heard all the loud cutting calls, etc. and most likely will respond to softer calling now. Try that calling sequence and be quiet for 15-20 minutes while scanning the woods for movement. Most likely they will sneak in quietly and show up very close before gobbling. Keep your movement to a mininum as well. Patience is the key now.