I did wonder if this had been designed a purpose "weak link", as the size of the thread and amount of stitching was disappointing. However, I can see not reason for a "weak link".
Initially I glued the webbing and then stitched it using waxed sail makers thread. It was necessary to drill 1mm dia. holes for the needle.
It was then necessary to lift the metal fixing at the front of the casing, so the centre board was raised and therefore I could gain access to the attachment hole. The metal fixing was held up by some blocks of wood. Once the webbing was reattached it easy to lower the fixing and board back in place.
The photo above is in B/W due to the un-natural lighting in the cabin, which lead to some misleading colours.