If you have a bad ballast for the fluorescent light in your marquee (a.k.a. header) here is a listing of the correct 14 thru 20 watt ballast to buy at your local Home Depot or Lowe's Hardware.
Home Depot (prefered):
SKU # 936-367
LC1420C651
barcode 781087101308
Advance Cat. number LC-14-20-C
$3.50
Lowe's (second choice):
Sylvania model 48307
Item # 82071
barcode 046135482014
Ballast 1F20 (48147)
$5.17
The one from Home Depot is an exact replacement and is priced reasonably, too.