magnaclean professional 2 leak problem

Hi All
I have just cleaned out the unit which I have done before, tightened up the top with the proper plastic lid clamp but there is a leak coming from beneath the top lid
I have tightened it up as far as I think ive done before but there is a leak dripping from beneath the cap which I can't understand how it has come about.....if I try to do it up tighter I could damage the other screws which are actually connected to the system........I cant think what I have done wrong.....I screwed it on hand tight with no resistance and then tightened up, any ideas please

Try a seal kit. They come with large seal for lid.

http://www.adeyspares.co.uk/magnacl...essional2-micro2-professional2xp-seal-kit-p50