if it was working ok before then possibly when its small cable was put into the big cooker connector it could have been pushed in too far so the connector screw came down on the insulation of the cable and not the copper conductor and there may be only a stray strand making contact. Remake the connection doubling up the copper wire to make a better connection. Incidently if your oven is a single oven capable of running off a 13amp plug then its best to lower the fuse rating to 15amp. (unless you have an electric hob connected as well if so leave it at 30amp) Cheers
Kenjo
August 2012