That additional bridge rectifier should be removed and original wiring restored if LEDs are installed. This common modification was put in series with the switched illumination bus to cut down the voltage to the 555 bulbs.

I installed dozens of these years ago in the distributor and route days as EBDs used to eat boxes of bulbs weekly.

The fluorescent bulb and starter are for the eight watt bulb behind the backglass. If that bulb has been replaced with LEDs that are not using the 120 volt line, these items can be removed from the game (as in my EBD LE)