Well, that depends which winding/s you're testing.
The secondary should read in the range 2.5-5 k ohms - measuring between the plug lead and either the cutout terminal or the stator laminations.
The primary should read <1 ohm, measuring between the cutout terminal and the stator. This test can only detect if the primary winding has gone open circuit.
The only way to test the Magnetron electronics is to disconnect the cutout wire from the coil, and test for spark, assuming the primary and secondary tests above are OK.
The Briggs Magnetron coils are generally very reliable; but they either work, or they don't, as a rule.
