The one you are showing looks to be in good condition and I doubt that it needs repaired, but I think it could be done.
To use it on a 12 volt system you would need to change the bulb under the green lens unless it is a neon bulb. You would also have to change the flasher unit to 12 volts. Other than that you shouldn't have a problem as long as you get someone to wire it who knows what they're doing.