Agree with above.
In my experience, these things usually only have two moving parts.
1. The compressor unit. This is the big black lump usually at the back at the bottom. They usually sit on some sort of rubber mountings and it may be worth checking if anything around that area is loose/rattling. As above, just moving the appliance a bit can help a lot. If it's a a problem inside the compressor, there's little you can do other than decide whether the machine warrants a replacement.
2. They have a fan which circulates cold air from the freezer part, around the fridge part. It will probably be behind a panel on the back, about the same level as the freezer element. This is usually pretty silent, but it is possible something has moved and the fan blades are catching something.
Our last machine had such a fan which failed due to worn bearings. I got a replacement for about £15 from our local 'Allspares'. (It's where all the pro's go) They give advice as well.
If it is an 'auto defrost' machine, make sure you don't disturb the thin white heater element wire, or if you do, put it back exactly where it was, to avoid getting problems with ice build up.
Mull
