I don't think someone would bother with the tape so my gut says it's factory. What happens if you measure the resistance over that resistor?
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The waterproofing schmoo makes me think it's factory. If you're getting 0v at the rear connector there's a break in the line somewhere. You'll have to measure voltage along the wire to see where it drops. You can test the ground by checking for continuity between the negative connector and the body/frame.

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