I called the manufacturer who is taking all three of the EM's back, one of them well used. They say they heard similar complaints around the time I purchased mine. They are sending me replacements from a new series that they say is "kicking butt", whatever that means.
I saved my test block and will run a new series of tests as soon as they arrive. I'll report then along with the name of the manufacturer if the results are good. There is no "A" in their name.
Vern