Just check mine , its definetly slack - I can get a screw driver in one side and my finger in the other !
I have a very small crack on the slackest side , and nothing on the tighter side.
I am not to worried about the crack - its at the "keep an eye on it" stage.

What I am stuck on is the tightest side is at maximum adjustment already - the strap buckle and the post the screw goes through are in contact already. It must have been like this since manufacture - I have had the car from new and this area has never been looked at.

I could start putting spacers between the belt and the chassis , but that feels like a bodge. I need to in effect make the belt shorter , so I can back the adjuster up a bit , to then have some adjustment available to tighten it - hope that makes sense. Anyone any ideas ?

I did take some photos to help explain but they are too dark.