LEDs
Arcade LEDs come in a variety of voltages. For most DIY use cases, 5V is the correct voltage to buy. Other options, such as 6.3V and 12V are available and will work, but will appear dimmer.
The correct size of LED is referred to either as 555 or T10 wedge.
This page will list stores by region.
Contents
North America
USA
Comet Pinball: https://www.cometpinball.com/products/2smd-bulbs
Europe
France
Small Cab: https://www.smallcab.net/led-c-88_123.html
Jammastar: https://jammastar.com/gb/122-led
Asia
Japan
conn-lab: https://conn-lab.booth.pm/items/2411066
Korea
ISTMALL: https://www.us.istmall.co.kr/Product/Detail/view/pid/51/cid/161