He has a design defect that causes him to explode if he stops moving for more than two seconds.

This was a simple design defect, and not related to the unique geometry of the secondary.

There has been no major refurbishment done to the station except for the replacement of the converter transformers in the mid-1980's due to a design defect.

This particular amplifier contained a design defect whereby the pad and equalizer plug in modules would literally fall off the circuit board when the device was opened.

Such a test might well have revealed the design defects.