Fisher, Teknetics, Bounty Hunter are the same.. I like mine so well I have two.. Wore the tips off both and First Texas replaced them.. Now I put about 2-3 layers of epoxy about 1-1 1/2 " up the tip.. When hardened I make a form with tape extending out from the tip and fill with epoxy about a 1/4" and let dry.. When fully cured carefully file into a sharper point ( checking with a light source from the back)..
Go slow and don't file and sand through the epoxy coated sides you first applied.. This makes the tip durable and can be touched up when necessary.. Also with the sharper point it penetrates the soil easier..
I also remove the knob and cut some closed cell foam rubber and place it over the stem and replace the knob to help keep the dirt out and to keep the knob where you set it..
As far as the battery goes do what was stated in the previous post or carefully spread them some.. Also a coat of silicone grease on the seal will help some.. Remember when looking at the cap from the side the prongs are toward the bottom of the cap.. That's the way it goes back on, prongs toward the bottom of the body..