It is bad news, though for the next sentence or two I suspect I will have to get my tin hat on, and avoid incoming fire. I was going to buy a plough gauge at some point, but Dixon's demise pushed me into buying while there was some available. When it arrived, I could see some significant problems they must have faced. The build and finish were poor. The bar that holds the roller was bent, and when adjusting the height, the far end performed circles. When I disassembled it, the bar had deep hammer and vice jaw marks in it. the measuring bar had vice jaw marks, and the stop wouldn't slide to less than 3", as the bar was thicker at the root than the end. There were other problems, but this is enough to give you a feel for it.
You may say this could have just been a rogue unit, but at £300+ it should not have been let out. Fortunately I can fix it, but it will be a few hours work.