I have a starter which I would like to add to the launcher. When I move the starter from the dash to the launcher, it will be added but you cant see anything as the symbol of the starter is lost. The empty space that represents the launcher can be used to start the script. Any ideas how to keep the symbol?
The icon that appears in the launcher is controlled by the .desktop file, mime type application/x-desktop, for that application.
In a .desktop there is a line item starting with "Icon=". that is where the location of the icon goes. Those desktop files are what you drag into the launcher.
By starter I can only assume you are actually talking about a .desktop file. Unfortunately the treatment of these .desktop files in Nautilus makes them difficult to edit. The displayed name isn't the actual file name and no editor is offered as an option to open the file.
What you need to do is use a terminal window and cd to the folder with the .desktop file. The system keeps them in /usr/share/applications but I suggest you keep any you've changed in ~/.local/share/applications. Do an ls in the folder and you'll see the .desktop files listed with the file names you'll need to edit them, for example on the CLI gedit file.desktop.
When you add your edited .desktop file to the launcher open the folder containing it and drag the file to the launcher. The .desktop files Nautilus shows in your .local folder may or may not be displayed as the application icon but as a generic text file with a .desktop name.
This is the process that works for me.
Restart Unity by logging out and in again or just Alt+F2