On my 300CE24 - 91 (M104 engine) I've got an intermittent noise: like squealing 1/10 of a second every second, that I suspect to be originated from the accessory belt.

First guess was to check Belt tensioner position. I was surprised (see attached picture) to see that the pointer is in position that I called '0' on the picture: I was expecting it in position '1', the higher part of the triangle shape.

What this position should tell about the tensioner: bad setting or damaged one?
Should explain my noise?

Thanks,

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