Lowrance X50 ds

new boat came with an X50, used it last week for the first time, would lose the bottom
running, at idle, and sitting still. went through the settings changed sensitivity and a few more finally gave up. went back yesterday same thing. went through settings again changed from 200khz to 83khz and it started working, no problem after that, changed back to 200khz and it would quit everytime. any suggestions ?? I'll probably send unit back just wondering if I needed to send trasducer too or just df. thanks for any help

when you say new like brand new or new to you

brand new