What event caused an accidental broadcast of a test script advising viewers to tune to a specific channel during the EBS era in 1971?

Answer

A technician pressing the wrong button during a routine test

The inherent risk in manually operated analog systems was highlighted in 1971 when a technician accidentally pressed the wrong control during a routine test, resulting in an unplanned broadcast of the test script.

What event caused an accidental broadcast of a test script advising viewers to tune to a specific channel during the EBS era in 1971?
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