Thank you for your help, but I’ve been in contact with Humminbird technical and even they are scratching their heads.
I’ve been an owner of several Humminbird side scan units for over 10 years now, and I’ve tried all the reset tricks and settings you could think of. I thought I was going mad, but it looks like my unit left the factory with faulty firmware.
I’m just waiting now to see what they want to do about it.
It’s a fab unit, and apart from this small problem, I’m very pleased with it.
So, thanks to all of you for your support.