Come on, at least TRY to help yourself a teensey bit. Crank up Google search and search for, say, "New World Twinline 3000 spares"
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July 2015
All sorts of places will sell you an oven door seal. Internet searching will help - perhaps the text - Domestic Appliance Spares - will be a good starting point.
Give it a try...
July 2015
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howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix gas cookers.