Warranty situation is pretty well covered in this thread:
http://www.findmall.com/read.php?17,1726422
Jay Evans is technically correct, but Tesoro normally goes above and beyond as long as the detector isn't obviously abused or a modified the unit.
Sand Shark threshold is not super steady. It can also become very unsteady when you get near interfering sources, such as some other detectors, wireless repeaters (some of the resorts and beach hotels are hard to get close to due to this one) and I think, when near an inlet, I was getting some interference from ship to shore radios as the ships were coming into or leaving the inlet. Have not had interference so bad that it could not be used for strong target responses, but I am sure faint (small and or deep) responses could fade into the disrupted threshold.
Were you either in the water or hunting along the sand at the point between dry and wet area when you got it sounding off at one end of the swing more than the other? If I am hunting parallel to the water line either in the water or at the wet / dry transition I've had that to some extent. If your scoop is at the side that sounds off more than the other, it could be picking up your scoop too. Sweep speed changing at the end of a sweep and change in distance to the sand or waves moving sand over the coil can all give a bit of a threshold change, although the Sand Shark is more immune to sounding on those conditions than some other PI's. Actually sounds like you are listening closely to the detector and are going to do well with it.
Cheers,
tvr
