Equipment miniature neons become dim with long use due to electrode material being deposited on cool glass.A simple circuit of four small components can replace the neon
1.Series capacitor 0.22 or 0.33uF 250v ac WKG
2.Bridge rectifier 100v 1A.Available 6mm dia. by 6mm high
3.Resistor 1KO 1/4W
4.Bright red LED [two or three in series if space allows]
Capacitor connects mains live to bridge,mains neutral
to bridge return. LED in series with resistor from bridge
+ to - observing LED polarity.
Capacitor acts as wattless current source.
Resistor limits switch on surge.

J.E.Smith, November 2010