Metal Transfer onto a Resistor Body Can Reduce Electrical Isolation

What the evidence preview establishes

Conductive metallic marking on the resistor body most likely contributed a parallel leakage path. The subject resistor carried substantially more extraneous metal than the controls, although some marking on control parts showed that the transfer mechanism was systemic.

Why this case matters

Treat component-body cleanliness as part of high-voltage isolation control. Prevent component-to-component rubbing, inspect insulating surfaces for metallic transfer, and compare suspect parts with controls before assuming an internal resistor defect.