6speedy3
I had a similar problem with my 998. The DI screen would flash when that page was displayed either by View/Exit or preset #2.
At the same time the quality of the SI display on the unit went to unreadable.( deep or shallow ). 2D was fine.
Returned unit, including transducer, to HB ($40.00 shipping and insurance ). Report-- No problem found-- updated software to 6.18. $65.00-- thank you.
Since the units return I've recorded about 5 hours-- so far, so good.