1. What clue indicates the non-working flashers are not the bulbs? First change the bulbs, then work backwards through the circuit.
2. The DMD problem appears to be age related "gassing out." It doesn't look bad enough at this point to change out the display. It would be best to check the voltages coming into the display before replacing the display.
3. The crane can be touchy to adjust. If there is slack in the gear train driving the crane due to wear you may have to work at the adjustment harder.