newworld gas oven safety keeps cutting in?

hi i have a newworld vision g90m and every day for the last week the safety keeps cutting in. if i press time reset oven will switch on but in the last two days it has also happened whilst cooking. had oven about 5yrs now believe it could (by guessing!) be a loose wire but have no knowledge of electrical items. £160 service call out by company but would like to fix myself if possible. thanks for reading this.

jolene
March 2013