Hummingbird 787ci. New GPS puck, brand new ducer. Getting bad depth readings n although I know I was going it a straight line n verified by my 997, it showed me going it circles n the depth reading wasn't happning. Just kept blinking or reading 400-800 feet in 12-25 fow. Is the 787 shot? I restored defaults 4-5 times no help. Worked great the first hour then the problems started. Yes, I unhooked it, turned it off n on. Everything you could think of. I bought it used 4-5 years ago