leaking water?

my scandinova larder fridge (model LF6-137W) seems to have lost the capacity to evaporate defrost water. The defrost water now runs down the inside of the fridge and has to be mopped up every day from where it collects on the floor of the fridge. The appliance is 6 years old, and up to now has worked perfectly. None of the settings have been changed recently. The appliance was purchased from Comet, Swindon.