I had a vintage B&D angle buffer with an aluminum body and I was buzzed a few times by it. I could never figure out if it was the buffer, or me holding it at odd angles while buffing, and my body giving nerve/muscle feedback (sounds weird I know). If I recall correctly, it was not double insulated, but I re-corded it and grounded it. It got sold off and the Milwaukee stuff graces the garage now.
Yep, that cord could use a new lease in life as a first step.