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Benton:
Connect two 25 W incandescent bulbs to the main panel, one bulb on each phase. Watch the flickering of these bulbs.
If one bulb gets brighter when the other gets dimmer, then there is a neutral problem between the main panel neutral point, where you connected the bulb neutrals, and the pole transformer internal connection for neutral.
If one bulb gets dimmer and the other stays constant, then the hot phase of the dimmed light is the problem area.
If both bulbs get dimmer, then is there some large 240 V load causing the flicker.
You can use two voltmeters to do the same test, but the light bulb technique may be better because the eye easily can see both bulbs at the same time.
When you determine which of the three types of dimming occur, then that determines the next step.
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