There is a ksport thread filled with information on people who have had to call ksport for replacement dampers. You also have a one year warranty.
http://www.ksportusa.com/ should be all the information you need to call for a replacement, but just be make it easier their number is 480-829-8100 for the technical support line. They also have an AIM screen name but I've always found them to be a little slow on responding: ksportsupport. I've read that even if you are not under warranty you can still get them replaced under warranty if you lie to them about the date you bought them....not that I recommend you doing this. The replacement dampers are somewhere in the range of $100 but you can also have them send you a rebuilt damper and then ship in the damaged one which might be cheaper.