this is not a Uk model i believe but, as a general point, these rubber strips have conductive channels running through them, they will only work fully when corectly installed as you have discovered. Failing any markings as to the orientation of the strip it is trial and error. Mark the top right hand corner of the flat part with a marker pen, this will keep you up to speed on your trial. First intall the strip, try to get it central, see what the result is, if badly wrong, note the strip position, flip it 180 degrees, try again. if no good flip it end to end and try again, if no good try swinging it horizontaly 180 degrees. one position will give a fair result, this is the one to work on. both connections must be spot on, half a millimeter out is no good. make tiny adjustments you should succeed. finally finger grease on the conductive part will give no go results. microwave-repairs.co.uk for further assistance
patrick, April 2012