My module( control unit) for my PP died so I had a new one installed. It worked perfect up until that point. Now when we wakesurf and set it at 11.7 MPH it surges between 10 and 13 MPH. When we wakeboard and it is set at 22 MPH it surges between 20MPH and 28MPH. It won't seem to hold the speed. Any ideas on how to fix it?