[Dave Campbell]

Check the small plastic coupling between the cylinder and the shifter gear shaft. We've had bad issues with the outermost retaining ring staying seated when shifting from low to high. Our cylinder pulled the ring off and left the shaft in between low and high. The ratcheting noise we got (sounds similar to the clicking one you describe) is from our shifter "hanging" between gears since it cannot shift into high. It is difficult to see it under load, but if you can watch it shift with wheels off the ground, you may be able to eliminate the issue we had. As mentioned above, the pressure while shifting is also very important as that can be a possible cause as well.