Gafair

I've been using Cura for about three years now on all my printers, Wanhao i3 plus Mono price V2 CR 10 and Japanese i3 Only recently have had problems and every one of my prince there's an artifact a quarter way up that sends the machine into a searching. And doesn't seem to know what to do. the artifact appears as two squares hanging off two sides of the front that only seen when I look at layers in Cara slicing Any suggestions would be helpful. very confident with Cara trying to use other slicing software is going take me a little bit of time Thank you Monty