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You don't say what is wrong with the lights on the topper? Do they come on at all? Stay on? Some only light? None light? More detail is always good.

The lamps used on this board are specials not used anywhere else (161 from memory but check this) - are the correct ones fitted? Are they OK?

A very common fault with the board that runs these lamps is the bridge rectifiers cark it BUT don't go changing things until we get more info so we can determine your fault