Can anyone please advise of a solution. The rear right rear seat back (the 20% one without the guard and cover) is jammed in the upright position. Up to now it has always worked fine but suddenly its jammed and of course that also prevents the left/centre backs from being lowered due to the attached cover. The release lever seems to be ok and the red warning centre pops up but the back remains firmly latched in place. I've tried pulling pushing heaving to the point of brute force but the thing seems firmly stuck. Can anyone help please?