Hard to believe just how small some lamps can get. Grain of wheat, grain
of rice and grain of sand. The one in my digital watch is so small it looks like
a swollen spot on a piece of human hair.
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When having to replace 'tiny bulbs' consider conversion to LEDs . These are readily available (also the high intensity ones).
Although you might have to add a resistor ,they will last forever ...........or at least a lifetime.

Frank GM0CSZ / KN6WH