I don't have the WS-1001 (I have Davis), but I was wondering if there is a segment check on your console maybe at power-on. Otherwise, if you get the light "just right" at some angle can you see all of the unlit segments on the LCD? Is there a "minus" sign in the display? If so, it might be software bug and could be fixed with a firmware update. If there is no "-" segment in the temperature area that is a major design flaw.
Don't these outfits test their products? A temperature chamber isn't that expensive for a company that isn't run out of a garage.
Greg H.