Help! Oven keeps tripping circuit breaker!

[Acorn50]

I have an Electrolux EOC55200X that has had very little use since new as the house was largely unoccupied until last year. The people who rented it for 6 weeks left it in a really dirty condition so I had to clean it using the pyrolitic cleaning function. The oven came out lovely and clean but about 20 minutes after finishing the cycle it tripped the circuit breaker. I can turn it on but it trips the MCB after about 5-10 minutes and then once the MCB is re-set it will trip again if I open the oven door (even without turning the oven on). So, finally got round to removing it from the housing and found 2 areas of wiring where the protective sleeves at the spade connections are completely burned and brittle. These are at the oven lamp housing and at a safety thermostat. (see photos). All other wiring looks fine and the oven looks like new in all other respects but very concerned as to what is causing it. Any suggestions please?