This failure is basically caused by the power controller, power controller can simply disassemble overhaul. Power controller damage often two cases, one can not rotate the knob to adjust the power, always stay in a block, but the heating function properly. This is usually caused by plastic power controller to adjust the gear lever is stuck foreign body and other parts, you can remove the power control / timing integrated components, remove foreign objects, and then re-installed can be solved. Second, although the power adjustment knob can be rotating, adjustable, but not with its variable microwave firepower, always working in fixed fire gear (usually in top gear mostly). This is a power failure caused by regulatory function controller, removable power control / timing components, check the power control switch, whether the timing of motor damage. Those found badly damaged and should be replaced.mgfservice manual download site