My CDE/Hygain rotator control box seemed to go through 26V light bulbs every couple of years. Knowing I was down to my last spare bulb, last summer I ordered from Amazon.ca a bulk bag of 100 white LEDs (3.3V, 20ma), and one of those multi-packs of resistors (1,000 pieces, 1/4W in 64 flavours).
I used six LEDs on a simple perf-board strip, and one 270-ohm resistor, wired to the old light bulb socket. Affixed with some sticky tape, it works very nicely — wonderful cool white illumination across the entire meter.
As an optional add-on, I then installed a 1K potentiometer on the front panel, wired in series with the stripboard-mounted 270-ohm resistor, which allows me to finely control the LED output across a useful range — extending the life of the LEDs or boosting them to “brilliant” mode (just because I can).
Total cost: 26 cents, all in.
Time: about 2 hours.