NEFF U1461N2GB Door hinge problem

I’ve been to this oven and fitted hinges and sockets 3 times in the last year! Problem is the door does not close tight. It’s fine with new parts but a few months later they’ve lost their strength. It’s a TRIPLE glazed door and the parts are correct according to Neff parts list, so I wondered if anyone could suggest a solution.
The customer has another Neff oven with DOUBLE glazed door, no problem!