I bought a used boat last year that came equipped with a Garmin 178C GPS/sonar unit. The device worked fine until two weeks ago when it would not boot up properly. I called Garmin, and the helpful associate in Olathe, Kan., gave me two suggestions on how to fix the unit. The first was to update the software using a memory card supplied free by Garmin, although there was a $6 shipping charge and a $50 hold was placed on my credit card as a deposit.
The second was to remove the unit and mail it in for service. He promised me they would either fix it or send me back a new unit. The catch was it would cost $200 either way. The software fix failed, so I sent in my unit and within a week I had a brand new 178C ready for installation. Considering the price for this or a comparable new is well more than $400, and that my old unit was useless, I was very happy.
My only issue is the hold time required to get to speak with a Garmin rep. I called three times, and in each case it was at least 15 minutes, but in the end it was worth it for the level of savings I enjoyed.