Odd issue with interior dome light

[MidwestEK9]

Hey all. I noticed today while attempting to replace the interior dome light on my 98 EK9 with an LED light that the light, whether it's the LED or the original halogen, sort of flickers and surges (gets lower and also then brighter than the normal intensity) but ONLY when the dome light is on the "ON" position. When off, the light is off. When on door, both the OEM halogen and the LED light operate correctly and immediately come to full and stable brightness with no flickering or surging when a door is opened, and immediately turn off when it is shut. There is an aftermarket radio in the car, and it does not have keyless entry. But the door switch obviously works fine, so this is not the "jump the pins in the green connector" issue. Observation of the OEM halogen revealed a dark, burned tint in the casing compared to the completely clear T10/194's I had just replaced in the rear license plate lights (those were unburnt, and the LED replacements have had no issues).

I haven't yet pulled the dome housing from the headliner. I could just leave it in off or door for minimal worries, but all of the above suggests to me that the switch inside the dome itself is going bad. However, I don't don't know if that would cause the "surging" and going above normal brightness I experience, which definitely makes me worry. All of these tests were performed with the engine off, so it is not an alternator problem. Anyone ever had this issue as well? Can the switches inside be rebuilt or am I looking at scouring for a used unit, of which there seems to be plenty. Cheers and thanks for any advice.

 

[iRELOADED]

first thought I had before reading your second paragraph was that the switch contacts are dodgy. Might just need a clean. If you have corrosion on it you can get the flickering or surging