I went from a 555 versatile to a case 4420. With the 4420, by the end of seeding I would have to get a needle in my back so I could walk again. Never had that in the 555 and I was spraying at the same speed. Two years ago the seat broke in the 4420 and now it's down on the floor and doesn't move and my back has been fine. The seat won't be getting fixed while I have it