Many of us have older components lying around. Being able to test these components, reliably and conclusively will help, especially when dealing with vintage systems like modular synthesisers and retro computers.
A system designed to do just this has been created, called the "Retro Chip Tester Pro". $120 will cover ordering the base board, the power supply and some key components, plus shipping. The rest we can source locally.
See: https://8bit-museum.de/sonstiges/hardware-projekte/hardware-projekte-chip-tester-english/