Originally Posted by
canopus
It could also be that the cam on the J-tek has gotten out of cable "phase" (its not in the correct clock position relative to the adapter) so it might not be moving the cable correctly. The correct position is listed on the directions that comes with them, I could scan it in later if needed. I've been running my Jtek #2 for almost 2000 miles so far without issues after the initial adjustment.
I'm with canopus on this one. Have a closer look at the jtek pully. The cable wraps around this pully and crosses over a flat spot. If you are looking at the drivetrain, this flat spot should be in roughly the 1 to 2 o'clock position.
Also, it doesnt hurt to make sure that all your cable housing butt up against the guides and properly inside your brake lever.