I took the back of the seat off of my 190e to take the armrest off (it was in my way). There are two long sheet metal screws on the bottom of the back facing down. Once the back is off the frame holding the net is unscrewed from the inside like you said. My net was loose so while I had it off I tightened it by pulling the top string tighter and moved the retaining clip over. Putting the sheet metal screws back in is a little tricky, you have to try and feel for the holes in the sheet metal of the seat through the insulation. I thought I had the first time I put it back on and had the back drop off in my wifes lap resulting in a questioning of my abilities.