Very strange. Have you plugged/unplugged your disks a lot? Hot-swap backplanes are generally designed for ~ 50 cycles (plug/unplug). If you've done a lot more than that, then it's understandable why they'd start breaking.
It's the other side of the backplane, where the SATA cables plug in. The SATA power connections are particularly bad, they're nearly unusable now, so I have to use the molexes. I was just looking, and this case is about 3 years old, and it's been in constant use, with about 6 different machines in it over that time.
The rest of the case is obviously fine, it'd just need a new backplane PCB.
I'm quite pleased with the new case I'm using, considering the price (£33 delivered), it's nicely built, and take 6 HDDs and has two 5.25" bays. I'm running a 120mm Silent Typhoon in the front as the only cooling, and the HDDs are running less than 8C above ambient with the fan running at 500rpm off the Asus' Q-Fan system. The only other cooling is the PSU fan (seriously over-specced 600W OCZ 80Plus Silver unit, but it's the only PSU I have with enough SATA cables that'll reach.