What should be done if a manual toggle switch type motor starter fails to reset after a power interruption?

The correct answer involves checking for a blown fuse or tripped circuit breaker because these issues can impede the motor starter's ability to reset. When there is a power interruption, it can often result in electrical faults or surges that may lead to protective devices, like fuses or circuit breakers, tripping to safeguard the equipment and circuits from damage.

By identifying and addressing blown fuses or tripped breakers, one ensures that power is restored properly to the system before attempting to reset the motor starter. This step is critical for safety and helps to prevent any further damage to the motor or starter itself, as well as to ensure that the electrical supply is secure and reliable when the motor is restarted.

The other options, such as restarting the motor immediately or leaving it for 15 minutes, do not address the potential underlying issues that could prevent a reset. Moreover, replacing the motor starter would be premature if the problem lies with a fuse or circuit breaker, which is a more common and fixable issue. Thus, checking for a blown fuse or tripped circuit breaker is the most logical and safe approach in this scenario.