sentences:  Because of the nature of their rapid operation, and the importance of consistency and correctness, originating and terminating trouble indicators were employed, which illuminated lamps to indicate the source of and nature of trouble when it occurred.This allowed technicians to quickly identify and resolve issues with the equipment without taking it out of service to perform lengthy troubleshooting routines.Because it was often necessary to run tests on other equipment while locating the source of trouble, other test frames were located near the trouble indicators.