Randy,
I would start by confirming that the GPS Receiver is the problem. Try connecting your 997 to another Humminbird GPS Receiver to see if it will work or not.
If the unit works on a second GPS Receiver you should look at the GPS Receiver cable on your boat for any damage. Usually you can see where the damage is. If not too close to the connector or GPS Receiver itself there is no reason why some competent person couldn’t splice the cable for you (be sure it gets sealed afterwards).
Another option here is to call the Humminbird Customer Resource folks at 1-800-633-1468 and see what the cost of getting the GPS Receiver fixed is. This may take a little more time though. See if they can ship one out against your credit card and than just credit your account when yours arrives at the factory – can’t hurt to see if they can do this.
By the way: the Customer Resource folks here are still busy. Many are trying to take family vacations before the local schools start back and we also had a company wide meeting yesterday – so it was not a good day to try and contact them. Calling early in the morning is your best bet to get through quickly as well and avoid calling on Mondays as this is their busiest day of the week!
Greg Walters at Humminbird