I agree with @nrenter and @stringreen . The 5A's should be a step forward and if not, something is not working right. As you do, I purchase used, and have had equipment that wan't quite right (and not that I think I was defrauded, but the seller didn't notice). While not cheap, shipping the 5A's to Vandersteen and letting them go through them (especially since he does running changes on many speakers) is a surefire way to get them back to new condition.
I was a in a similar situation last year, my Magnepan 3.5's had a delaminating woofer. I was trying to decide if it was a good time to upgrade to a 3.6 or 3.7, but could face the same issue, try to fix myself, or take a chance on having them done by a third party. I ultimate ponied up, boxed them, spent the $250 to ship them to Magnepan. $1100 in addition from Magnepan for a rebuild and shipping back, but I got back speakers in brand new condition that I knew were checked and fixed properly by the manufacture.
I was a in a similar situation last year, my Magnepan 3.5's had a delaminating woofer. I was trying to decide if it was a good time to upgrade to a 3.6 or 3.7, but could face the same issue, try to fix myself, or take a chance on having them done by a third party. I ultimate ponied up, boxed them, spent the $250 to ship them to Magnepan. $1100 in addition from Magnepan for a rebuild and shipping back, but I got back speakers in brand new condition that I knew were checked and fixed properly by the manufacture.