Here's an obscure (and now archaic) definition of a word, from the Oxford English Dictionary (asterisks mine):
10. (U.S.) A fault, a defect. Obs. rare.
In quot. 1886 used of a flaw in the insulating covering of an electrical conductor.
1886 Sci. Amer. 15 May 308 The consequence of neglect might be that what the workmen call ‘a n****r’ would get into the armature, and burn it so as to destroy its service.
It's similar to the modern "gremlins" as a term for mechanical failures. It's also got nothing obvious to do with the colour black. It was clearly in use reasonably commonly back then - even if it's unknown now - to get into Scientific American and thence into the OED.
I imagine, if language hadn't already changed in the last century, there would be people using that word instead of "gremlins" and claiming with a straight face not to be meaning it "in a racist way". It's not possible to use a term associated with a particular race (whether or not that term is in itself insulting or negative) as a negative description for something else and do it in anything other than a racist way (and the same goes for other types of prejudice).
It's not the only definition that's clearly intended to evoke that "this [thing] is bad like a black person".
