The term isolation can also mean insulation or spaced sufficiently to prevent arcing or creep. They are talking about the phenolic being in good shape to keep the metal tabs/screws from touching each other and having proper fender dimples to keep board up off (insulated)(isolated) the inner fender. Just a warning to check everything new and old. We don't know if, for instance, the mounting of the board was over tightened or mounted wrong.

It is super crazy to use those. Totally unnecessary extra connections. They were discontinued in the years after this.

The other isolation meaning used when speaking about troubleshooting was explained already, as you know.

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