Looking at the spare hinges (Something YOU could have done for yourself) there doesn't seem to be any scope for adjustment:
http://www.bekospares.co.uk/cf374w-7515020004/catalogue.pl?path=110911&model_ref=11337233
Replacement would seem to be the only course HOWEVER, is it possible the space between the lid liner and the insulation is full of ice? That could weigh the lid down, even with good hinges.
XXX
November 2016