4638 BT Tricity Sovereign - how can fix oven door?

My parents' Tricity Sovereign oven door needs an elastic bungi to hold it in place. Otherwise it tends to drop on your foot when you are standing in front of it. It is also a bit of a bummer if you are trying to roast the Christmasw turkey! help

I know that some clever person out there will know which parts are required and how to fit the.