Kuppersbusch microspeed plus tripping circuitbreaker

Hello all would welcome your views on this problem.

I have the above which is a combination oven / grill / microwave.

The unit has only been used on microwave and works fine.

Come xmas day I needed the oven, a minute after you switch on it trips the circuitbreaker.

The oven works fine on grill mode

the unit is 4 years old, stupidly i did not test the oven function upon installation…….

All power supplies new / uprated upon installation.

model number EMW K9600

Any suggestions

Thanks in advance