How to check if a switch is failing?

Determining whether a residential wall light switch is failing and requires replacement involves checking for physical, mechanical, and electrical warning signs. Key indicators include a switch handle that feels loose, mushy, or fails to snap firmly into the "On" or "Off" position, visible dark soot staining or melting around the toggle slot, a switch that feels warm to the touch, or lights that flicker intermittently when toggled. Additionally, testing with a multimeter can confirm internal contact resistance. You can troubleshoot switch wear easily through visual checks. You can verify that your corrective action is successful when shutting off power at the breaker, replacing the old switch with a new rated toggle, and testing the circuit restores firm snap action and reliable lighting without flickering.