After solving the KXPD3 PC board misalignment that caused the knurled screws to be hard to turn by drilling out two clearance holes for the board mounting, I started getting erratic CW, as some others have reported.
Here is my theory:
The connection between the paddle arms to the ground that needs to be closed is through the pivot pin at the back of each paddle arm. The pivot pin has one end that is necked-down and has not been ground to a bright finish. In my paddle, that end was in the bottom and, I believe, was making intermittent contact. I reversed the pins, putting the shiny end down and, so far, that seems to have cured the problem.