Well, I checked it and must say that this is not really what I was looking for.
Instead of fixing a design flaw the problem is 'cured' by rollers attached to the frame? I am sure the german TÜV (MOT) will question this. Instead of installing such obvious hints that something is not perfect I better leave it as it is then. Once TÜV/MOT is due I'll clean the rubber marks on the stays and give it a try....
