Put it this way...

I make lights.. thats what i was trained to do 27 years ago. I buy raw glass tubing... bend and blow it to a design... process it and then sell it. I make my product, not buy it. In the 6 years i have been out on my own i have had a ZERO failure rate. Every now and again i may get a faulty electrode.. it is removed and the product is reprocessed. It does NOT leave my shop until i know that it will last 10+ years of continous use 24/7.
I buy transformers... electronic ones i can expect 2% failure rate due to variations in resistor values etc.. its a fact of life which i warranty against. I cant control this. If i get more than this rate i drop the product and source another.. simple.
My customers need to know that i sell the best quality there is and i pride myself on this fact.
Im sorry, but the product leaving Stern does not have the quality control it should... buying NIB should never be a gamble, its should be its own guarantee