Beko kdc653k Tripping rcd

I have a beko kdc 653k, everything works fine and as it should, except the main oven. When its turned on it begins to pre-heat, then it will trip the electrics.
Ive made a bit of headway with it today, managed to get it upto around 200 degrees, when the red light goes off, to say its at temp, it’s fine. But when the light comes back on to heat, about 45 secs later it trips again. I did this multiple times in order to get it upto 200 degrees.
Ive had the back off, no loose wires, even used a multimetre on an earth to see if i get a current spike when it trips. Nothing. The thermostat appears to functioning. It has contiunuity. Also a little naughty, I bypassed the thermostat to see if it still tripped. It did.
Last call was to remove the live from the heating element. All powered on fine. Obviously didnt heat! But it didnt trip.
So if an element is on its last legs, (still heating) is it possible for it to trip the breaker?
Just want to find some info before i get a new element. The cooker is only 2 years old! The air fryer gets more use! Thanks guys.

(UPDATE) so 15 mins after writing this post i tried an experiment. Took the cover off the inside of the oven, set it to max temp but left the door open. It didnt trip. Saw the the element was going red and hot. But a few mins after shutting the door, it tripped. so maybe it is the thermostat? Thanks again.