LOL, Can-Dance, That's on the link you posted!!

To sum up:

Unplug the oven

1-Put your cell phone in the microwave. Shut the door.

2-Do not turn on the microwave!

3-Dial the number of your cell phone. If it rings, you have a leak. If it doesn't ring, your microwave oven is fine.

The question is if your oven is hermetic ot not enough for the electromagnetic waves come in or out.

Haven't tried the fluorescent tube yet for large leaks.