The best way to describe what happens to the foam cushion is ’shrinkage’. Over the years, as it has been used, it loses its’ ’springiness’, causing the material to appear stretched.

Solution ? Very simple really. When you remove the ( lower part ) of the rear seat, you should place it upside down on a suitable surface so you don’t ruin the seat - preferably place it on your lounge room floor, on carpet. 

You will notice the metal frame and the ‘gaps’ between the frame and the foam cushion. When you see these ‘gaps’, you will understand what I mean by the ’shrinkage’ that I referred to earlier.

For this step, you will need some old clothes, or rags. Really though, you can use what you want so long as it does the job. Place the old clothes ( or whatever you are using ) behind the metal frame so as to fill up any ‘gaps’. 

I know that this is a no-frills way of doing this, but it works perfectly.

Once again, the photo’s I’ve provided below are self explanatory.  

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