Signs are just another specialty end of our business which requires training, stocking related parts such as sign ballasts, H.O. lamps with various socket styles, neon transformers, glass housings, and a decent bucket truck. I'll only service a sign, indoor or outdoor, if I can reach it safely as a courtesy to regular customers. Removing plastic sign faces can quickly turn to tragedy, wind or rusted frames can ruin your day.
In order to sevice neon signs you have to have a neon shop available to actually repair and repump the broken glass and be able to give them a good template to remake it if it's too badly broken. Outdoor neon transformers are typically 15000 v., 12000 v., and 9000 v., the milliamp ratings are usually 30 or 60. Ground faults are very common as you might imagine and the longer it's left in disrepair the more damage tends to get done due to the high voltage seeking a path. You could easily fill a large van with all the sign components you might need to do repairs on a regular basis. In general, best to let the sign guys handle it, it's their bread 'n butter.