We bought this new system microwave/oven 27'' combination. After installation, the microwave works, but there is no heating. And based on information we learned from a GE technician, the magnetron may be to blame. But I wonder what sort of QC that GE has in place to test the instruments before sending to customers. It is a time-consuming process and costly since we had to pay a subcontractor to install the system, and we soon be disappointed and struggled to see why this happens.