I have a 48in shoplight with one actinic and one corallife bulb. It has been setup for about 6 months and was working fine until last week. All of a sudden when it comes on it is barely bright at all. If i tap it it turns all the way on and if i leave it alone most of the time it wil get brighter after a while. What should i do? I have already taken the bulbs out and put them back in to make sure they are in right.