Carol Flynn-johnson , I do not own one of these, I will post a video link below to show how to remove the top, that way you can check the wire connections and if able test wires with a DVOM to see if bulbs burnt out or not getting power from the small control board. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
https://www.youtube.com/watch?v=Z8N9rv9Muvw
http://www.mcssl.com/store/suntronicscomponents/mrchristmas