Thanks for the replies. 996Pilot got it exactly right. I pulled the passengers side lights off and corrosion at the ground was obvious. You've got the copper wire & hold-down, steel set screw and mounting screw going into the aluminum frame member! Everything was cleaned to bright metal, re-assembled and tested and all the lights come on bright, and operate as they should. And since all the tools were out, I repeated on the drivers side, where corrosion was also observed. With luck this will solve the problem for a long time. Thanks for saving me a lot of time, 996Pilot. Tom McCloud