Question #1--Some days they just don't gobble--depends on lots of variables--where the birds are at in their reproductive/breeding stage, weather, sun, clouds, temperature. If they are with hens, they will usually gobble before they fly down, and at least once each time after they breed, kind of a "that was wonderful, who's next" gobble/shout.

Question #2--You could have. Then again, are you looking at a spring roost or a winter roost?? If winter, they could have moved, not from being spooked, but to a spring roost instead of a winter roost.

Question #3--If they're not gobbling, look where they're likely to be, maybe set up and wait. If I don't know the area strut zones well, I go to field edges till 10-11:00, then to cool shady bottoms, if it is hot, and hang out at roost sites (but 100-150 yards off, and on the ground, not moving) till dark.