GI lights. They don't actually go through the rectifier, but the lamp rectifier is BR1 on the power board. That one I listed will work as a replacement if you feel it's needed.
Check the yellow wires that come into the power board on the bottom right, and there is a little jumper just below the big heatsink near the relay on that board as well. Check that too. Mine burned up so bad that jumper de-soldered itself from the board and was causing GI sections to go out. The yellow connectors tend to burn also...mine is charred PCB and soldered directly to the board...there isn't a connector anymore. It came like that. =\