I seriously doubt they would be doing me a favour. The conditions of Bitmain's mine might not be operating in reasonable conditions, and such could cause degradation. And running the machines in their own mine for a certain amount of time could diminish the machines life capacity. Then sending the same machines off to a customer who does operate in a reasonable environment would be setting that customer up to fail. So in my mind there are no favours given.

But I take your point about the bathtub curve of failure, that is a possible reason for my situation. Or to quote NotFuzzyWarm from another post "To squeeze out the highest possible yield of the 16nm chips Bitmain has seriously widened the QA window for what are "usable" vs good vs Prime chips". This is another possibility. Whichever the reason, Bitmain in my view cannot be trusted to provide a quality product, or a quality customer service for that matter.