Hi I have a Braun BP 3550 (or 3560? Type 6084). I used to use it religiously years ago - and knew how to fit it - but then I consistently got an Error 21 and gave up. I have need to use it again now. I see in the manual that an Error between 1 & 29 is to do with positioning but I can get no further information. What precisely is an Error 21 please (as I've successfully used it before but can't seem to get it working again!)? Thanks, Chris Warrick chris.warrick@gmail.com