Issues aligning flexible z-axis coupler

I recently purchased a chinese prusa i3 ctc reprap printer, it was meant to be a cheap first foray into printing and it worked great. However over time my z-axis rods warped due to them having room to move at the top of the printer, so when ordering new rods I also ordered one of the flexible metal couplers rather than using the plastic tubing that had been supplied with the printer. The coupling has arrived however still waiting on the new rods, but when I try to use the coupling then no matter how I tighten the end on the 8mm rod side it always ends up sitting off the center of the coupler, meaning that it has even worse z wobble than it did with the plastic tubing. Is there a method I'm missing here for tightening the couplers that would stop this, or should I just assume this rod is bad and wait for the new ones before trying anything? Thanks in advance

Wrap a single layer of electricians tape on one end, slide the lead-screw with the taped end into the coupler.
Trim the tape extruding around the lead-screw for looks. This will allow the lead-screw to turn true.