Well, wouldn't you know it. I got my TV-7A/U tube tester out. to check the tubes in my R-390. The 3rd switch (mul cond) on the push-buttons would not work. It was completely inoperative. Can somebody give me any hints before I open it up? This tube tester is the only one I have and without it working I can not test my R-390 problems. George KA5DEN 10X 74681