I suspect that Skydog may have a good suggestion (and considerably less expensive than a new $20 charge cable from Amazon.)
As far as the construction of the microUSB port on the KF, itself, I think it's simply cheap manufacturing. I noticed a slight bit of play in the connection when I first received my KF. As a result I've been extremely careful about attaching the charge cable. (No wiggling, no forcing). It has remained completely functional for three months with no change.