[drh4683]

The tumb screws are most likely the yoke position clamp, loosen it and you can turn the yoke left or right for correct raster position. The round thing is your blue lateral magnet. By turning it, you will notice the blue convergence will move left and right depending on which way you turn it. Its serrated so its easier to turn by hand. Since it was moved, go to a stable channel (like the prevue channel on cable) and touch up that lateral magnet so the blue merges with the rest of the highlighted immages (anything white in color, like numbers or letters on a commercial). Even though its back where you had it, if its 1/32" away from its orignal setting will show on the screen.