Ray, I have the same issues with ours. I believe GS uses Vista lighting but here are some others. Ours is a channel set lighting strip but there should be three, one on each side of the step well and one at the rear. All I have is the rear one now so I need to take it apart and measure the sizes. Here are the links that I have.
http://www.vistamfg.com/
http://www.platinumlightinginc.com/
http://www.innovativelight.com/accent-a ... c_1456.cfm
Let us know what works and how you fixed it as GS is of no help these days.