The part concerned is a 2-part white nylon thing, about 140mm long (see photo). The two halves clamp together like a razor shell around both ends of the motor chain and are held together with integral side clips plus 4 screws along the central axis, effectively completing the chain. Mine snapped when the closing overhead door caught the roofbars on my car.... One half of the connector bears the number 8007133 and the other 8007014.
Not sure how relevant, but the door is a Cardale Vertical S/A Futura (AVSR 1470 – 4128 x 2000) up and over type, installed c 2001, fitted with a DC650N motorised operator.
If anyone can point me in the right direction, I shall be very grateful
Thanks in anticipation