I bought a used Frigidaire table top microwave used, about 2 years old, but there is absolutely no label with the model number anywhere, looked inside, outside, underneath, no labels. Anyway, I noticed the ground prong on the power cable missing...is it safe to operate the microwave with the ground prong missing, or should I find a replacement cord and install it myself. Where can I purchase a replacement power cable for a microwave that has no model number/serial number label?