One of the bulbs is not lighting up. I tried a new bulb and replaced the ceramic bulb holder and that did not help. What am I missing? Could it be a transformer that suddenly went bad? If that is the case what options do I have given that the transformer is buried in the ceiling. I have researched buying a separate transformer but it appears difficult to find a dimmable 10W transformer assuming I can get to the main wiring without ripping up the ceiling. Any ideas would be most helpful. Also, do I need a dimmable transformer? Or will a constant work with a dimmer switch?