Cata larder fridge ice on back wall and not cooling properly

[lewis2010]

Hi guys i am after a bit of help please , my Cata larder fridge LF177Bl has started playing up .
Ice has stated to form on the back wall at the top and the fridge isnt as cold as before .
The compressor runs and the condessor coil is clear . I'm guessing it could be a fault with the defrost system but I cant see how to access these parts . There is no panels to remove inside the fridge and the back is covered in foam .
Any help please guys would be much appreciated

[redroge]

Could be short of gas sensors are probably foamed in at the back of the fridge

[lewis2010]

the foam at the back will not come off in 1 piece , if i break the foam will it affect the cooling

[frank]

Start with a 24 hour defrost with the fridge unplugged and the door open - then see how it performs after that before you start ripping anything off.