Was out on the lake today and noticed one of my bow units had 2 black dots on the screen plus a few black lines at the top of the screen. On the load up screen they are not present but pop up later. Any ideas? Since its the only unit on my trolling motor transducer, and none of the others are having issues, I was thinking transducer issue. Thanks for any ideas

I'm afraid my inclination is to say the transducer isn't causing the display defect. It appears that you have a map screen selected. As a diagnosis step to answer your own question, power the unit up, observe the same issue, then disconnect the sonar cable from the back of the failing unit. If the screen defect still exists, the transducer isn't causing it. I don't believe that it is, but this test would confirm it.

Second test: Does this happen if the network cable is disconnected? (If so, this excludes any networked mapping as the issue.)

Third test: Do you have a map card in the unit? If you do, remove it and power cycle the unit to see if the defect still exists. (You could have a map card read failure.)

Fourth test: Does this still happen if the trolling motor breaker is turned off? (This will exclude interference from the trolling motor.)

I predict Map Card fail.

After you try all the other suggestions, try turning off the screen overlays. I doubt it’s associated, but I’ve never read/seen a post like this before, very odd indeed.

Update: disconnected the unit and connected the cables to one of my detachable units. No issues. Therefore Im guessing it is the unit and not transducer. No map card in it. Still does it with network cable disconnected and trolling motor breaker off. Noticed this morning that the black spots are not present at the HDS initial power up screen, but are now visible on the accept page. They are also present on sonar screen. So I'm guessing it is now a screen issue. Time to get to googling

It sounds as though you covered all the bases I had suggested, and none of those appear to have had any influence, so it seems you are down to "bad unit".
Try a soft reset next. Save your waypoints (even if they are also on another unit), and try a full factory reset as a hail mary before you decide it has to go for a trip to Oklahoma.