Not certain on the w126, but on the early w124, those wire rods where also hog ringed to the pad. The rings will be buried deep on the underside, it is best to work your fingers along the sewn rod end and find the staple/hog ring points. They could also be Stitched with thick thread or twine if the covers where previously replaced.

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)