The circular glass antenna cover cracks when a food deposit is left on it, every time the microwave is operated the food deposit cooks even more untill it becomes like charcoal and super heats in a small area causing a hot spot and the glass cracks. You can easily replace it yourself if it is still available, it simply turns anti clock a 1/4 turn. (2 minute job avoids a £90 + Bosch call out) Cheers
Kenjo, August 2012
