Duntech repairs?

I would send a note to both Madisound (since they previously sold Dynaudio) and Dynaudio, asking about the model numbers. The similarity of the numbers suggests they are all the same manufacturer.

If all else fails, you might contact Millersound, explain the situation, ask if he will evaluate all four woofers, and then rebuild as necessary to make two matched pairs.

This may all seem like a great deal of trouble but I suspect you will find it worthwhile once you have your speakers performing up to spec.

Apart from Millersound being able to repair the woofers, I know that Bill is a huge fan of Duntechs.

Since we've never talked about it beyond him consistently the speakers me, I'm not sure how deep and intimate his knowledge of the products are in reality. My guess would be he possesses it.

For the record the Duntech Marquis had Vifa Drivers. I had the original drivers and they were Vifa with the original foam surround that started deteriorating. I contacted Duntech and they sent replacement Vifa Drivers. This was some years ago and I believe they no longer have a supply of the replacements. The replacements were same paper cone material and size and specs but the casting on the baskets were substantially improved and the surrounds were rubber. It was huge improvement, but a lot of it probably came from the fact that the surrounds were rotting out on the old speakers. The bigger cousins from what I understand are Dynaudio.

send the woofers to Bill LeGall at Millersound in Pensylvenia actually send him all the drivers and he will work some magic on those things that you can't even imagine

I third Bill Legall,
I had a original pair of Duntech Princess speakers and after several years I sent them to Bill to refoam the surrounds of the bass drivers and he did a fantastic job and the speakers sounded great in every way. I had them for over 20 years and sold them a year ago.
You will not go wrong with letting Bill look at them.