Smeg fridge making strange noise and not cooling ?

I have an old style smeg fridge, in the fact that it is probably about 6 years old. The type which has one door but an ice box at the top of the fridge.

It has starting making a very strange and loud vibrating noise whenever the door is closed and it doesn't stop.

We had started to notice that the seal was starting to fail and there is no contact in the top corner for about 4" but before paying for a new seal, I wanted to ensure the noise wasn't due to any other reason, because I'd hate to buy one for it not to work.

In your experience, does a new seal always work to make the door tight again??