Had a problem the same as this with a 899.

That is a known software bug in the Side Imaging units. Using a Chart Speed of 2 in combination with the Sharpness being used is what seems to be causing this. I do not know when this was fixed but it was with a software update.

Can't remember which update resolves this but make sure that you have the latest. Turn off sharpness and don't use chart speed. See if this works.

B-