George,
We typically fix and ship back the unit that is sent in to our Service Center folks. If we cannot fix the unit we will replace it but we try to avoid this so you get back your unit that you sent in. We’ve done this for the 25+ years I’ve been here and thought all sonar manufacturers did the same.
FYI: If you send your unit in with waypoints, tracks and routes and we have to swap out the unit, PCB or memory device: we will try and copy the Nav information over to the new unit, PCB or memory device so you don’t loose any of your precious hard-earned data. That being said I would still encourage everyone to save a copy of your Nav data on their computer before sending your unit in for servicing.