Chester,
I'd be rather careful working on innards of a microwave oven if I were you.
The reason being, not only the large currents that flow when it is operational, but also bear in mind that most m/wave ovens also generate in excess of 2-3000 Volts to run the Magnetron and no Multimeter (or body part, for that matter) will carry that amount of voltage without damage.
Also bear in mind that operating a microwave without it's cover in place could also expose you to large amounts of microwave radiation.
Be very careful, if you aren't sure what you're doing, take the thing to someone that does.
