Joe
I can't recall what made mine do the same thing, but it may be your cable from the coil to the main box is loose. Take it off the main housing and blow into the connections, as you may have something in there. It can also be that the wire for the coil is exposed somewhere and when you hit water, it shorts and starts to send false signals. Is there a lot of air planes and jets while your hunting? You also need to tighten but don't over tighten the coil to the shaft so it needs a little more pressure to make it flop up or down. Hope this helps, good luck at the hunt and God bless you all.
Philo_NY
I can't recall what made mine do the same thing, but it may be your cable from the coil to the main box is loose. Take it off the main housing and blow into the connections, as you may have something in there. It can also be that the wire for the coil is exposed somewhere and when you hit water, it shorts and starts to send false signals. Is there a lot of air planes and jets while your hunting? You also need to tighten but don't over tighten the coil to the shaft so it needs a little more pressure to make it flop up or down. Hope this helps, good luck at the hunt and God bless you all.
Philo_NY