Recently the dash lights at night have been giving me a problem. When the headlights are on and the lowbeams are active, I can see the blue highbeam indicator light on about 10% of its full brightness. When I switch on the highbeams, the blue indicator light is bright as it should be. Then switching back to low beams, the indicator is that dim blue light again. When it's in the dim condition, the white lights for the instrument cluster is a little dimmer than usual. I can turn the dimmer dial to off and the dim blue light will go out along with the rest of the lights in the cluster as they should.
What am I looking at as a problem?

Thanks in advance.
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'86 sedan with 445,000 miles on the original engine and automatic transmission