I've been working on this marquee the last months and I think I've finally reached a decent quality file. Far from perfect of course, but cleaner than the previous one at least.
(http://i44.tinypic.com/2gvivsi.png)
Steps 1: Getting rid of the yellowing.
(http://i42.tinypic.com/2lkyzwi.png)
Step 2: Cleaning the worst scratches, sky correction and boosting the colors
(http://i41.tinypic.com/2870l6p.png)
(http://i43.tinypic.com/jkktgk.png)
The final file is too heavy to upload it to Arcade Art library, but you can download the png file here:
https://www.mediafire.com/?lyrb4kn6a27ut7w
Feel free to improve it if you want, of course ;)
:)