My n308 freezer S/N EFF 102695which was bought in 2005 is now not freezing in the top 3 drawers. The fan is working. There is a big patch of ice at the lower back where the panel is. It started at the top drawer first a couple of months ago. Is this an expensive job to repair? I have defrosted it at the moment. My husband who is an electrician is gong to take the panel off to see if there is anything wrong.