What condition of Oxygen Tank No. 2 prior to Apollo 13 ultimately led to the sparking insulation and explosion?

Answer

It was damaged by accumulated stress from pre-flight testing, including being dropped and subjected to excessive heat and vacuum tests.

The tank had sustained damage from being dropped earlier, and subsequent testing that exceeded its design limits damaged the internal wiring insulation, which later sparked.

What condition of Oxygen Tank No. 2 prior to Apollo 13 ultimately led to the sparking insulation and explosion?
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