English: Technics RS-M270x mech with white replacement LED in place of (long dead) incandescent bulb. Needs very small 3mm. dia. (or smaller) LED to fit. Needs some clipping of the stock rubber mounting gasket. This is a very bright 6000 mCd white LED, much brighter at 10 mA (appr. 20 mW) than 60 mW incandescents. However, the yellow-green opaque plastic window blocks most of light output.

Datasheet says that this LED has two spectral peaks, a sharp one at around 460nm (blue - this is mostly lost in the prism) and a flatter one at 500...600 nm (yellow-green - it passes through albeit at a loss too). This is typical for phosphor-based LEDs: the primary blue LED ignites the yellow-green phosphorus via the Stokes shift.

Obviously, the existing 12V DC power supply cannot be fed into the LED directly - needs a series resistor (1kOhm 1W will do for a superbright LED). There's plenty of free space on the PSU PCB for such resistor.