I remove the dimmer and opened that unit, only to have the wiper pressure springs fly across the garage. Found both springs and cleaned the wiper portion of the dimmer with contact cleaner and fine emory. I also wiped down the dimmer coil. Used heavy grease to keep the springs within the recess of the dimmer knob and reassembled.
The lights are brighter, but could be better for my old eyes. I have not tried the LED types, but maybe next time I am in the cluster again.

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Gary
Experience is something you get, Just after you needed it....
'99 E300 295K, '83 300D 220K, '75 240D 185K sold
'80 MCI Bus Conv DD 6V92TA, w/4 cyl. Kubota diesel GenSet 12.5KW