Many years ago I purchased a used set of 2Ce Sig II's and one of the speakers had this exact same symptom. It was the 10" rear firing active coupler that the owner had fried.
I was comfortable with DYI so Vandersteen sold me the replacement.
If you are okay using a soldering gun and solder and have a decent, quality staple gun then you'll save a ton of time and $$.
I can provide more on my experience should you decide to go that route.