Still, if both the PP and the boat speedo are showing zero, that is a strong indication that there is no signal getting to them from the paddle wheel. I would look at the connections first, to make sure they are good. I used a scope to verify the signal from the paddlewheel, although I realize that is not likely in everyone's tool kit. If the connections are good, but both units inop...then replacing the paddlewheel would be my next step.