Signs are such a pain in the neck to get access to and get apart sometimes, my repair approach is about half troubleshooting and half visual. About 9 times out of 10, all the lamps will get changed. About 50% of the time an otherwise functional ballast will get changed based upon its visual appearance and how old my gut tells me it is. The lampholders warrant careful inspection, as they are prone to collect moisture, particularly the one's in the bottoms of sign cabinets that have the lamps arranged vertically. They rot out pretty easily. The action of the spring loaded ends should be investigated to assure solid contact with the lamp. Replace any lampholder end that feels funny, or has metallic parts that are otherwise corroded. It just costs too much to access a plastic sign interior most of the time to not do the "whole job" while you're in there. Business owners already know that a sign repair is generally expensive. With any luck, however, maybe it'll just need lamps.
