I have fixed two Sand Sharks. I fixed them myself. The problems have been mostly all in the battery holder and batteries. I have also replaced the batteries with three AA penlight Lithim batteries (2800Ma hour, Last for weeks) I used a three penlight battery holder and some foam to hold it in place or just hard wired the holder with leads long enough to remove the holder to take batteries out for recharging. There is not much to the Sand Shark, one IC that is everything and one transistor to drive the coil. At the bottom of the battery holder compartment is a small audio transformer to drive headphones. Give it a check yourself, everything can be removed from the case. One word of caution. clean seals everytime you open it up and lubricate with petroleum jelly. I cannot over stress this enough. I have seen so many Tesoros that have flooded.