Having trouble with an older Neon sign that has Dim areas? If so, turn the sign OFF then take the sign down. Now plug the sign into an electrical outlet and turn the sign ON. Take a hold of the sign by the frame and hold the sign up over your head facing you. Please be very careful not to touch the neon tubes as they a very fragile and could break. Look for the very tiny mercury balls inside the glass tubing that is dim. After you see them, tilt your sign so the tiny mercury balls move to the area of the tubing that is not lighting up. You may have to rotate the sign back and forth to ensure they have moved. Now carefully place the sign on a flat surface and leave the sign on for 20 minutes. If this was the issue, then the sign will regain its full brightness in the dim areas. Hopefully this helped!