When you say 'sync cord', do you mean an off-camera hot shoe flash sync cable, like this:
or something like this X-sync cord:
(And there are many more varieties of sync cord than just the two above) ...
With the hot-shoe extension cords, if that's what you are having problems with, why not just buy another one (from another brand instead of aputure) and try it out. They are cheap enough.
I have the JJC in the image above that only cost me about $15, and it works fine on K-1/K-3/K-5 (JJC FC-P3 TTL Off-Camera Flash Remote Cord for Pentax 1.3M). Cables get defects all the time - network cables, flash cables etc. Always worth having a spare.
Last edited by rawr; 07-20-2016 at 05:44 PM.