[Ron Ramirez]

If they are like the Lafayette LR-3500 I recently rebuilt, the tiny bulbs can probably be replaced with 3mm LEDs. I've found that they do not require a separate diode for AC operation but they do require an appropriate series dropping resistor; and in the case of the stereo indicator, it also needs a parallel resistor to simulate the current draw of the original bulb (typically 60 mA in incandescent stereo indicators).

I like to go over them with some sandpaper to make the clear surface opaque, causing the emitted light to be less directional and look more like an incandescent lamp.