Distributors that use a magnetic pickup can be easily tested to make sure the coil windings are intact. If no voltage is produced, the copper windings are damaged or broken, and the coil must be replaced.
How about the magnet, will it work even if it is partially cracked or if it has some iron dust on it? My engine only sputters around 3k RPM, doesn't want to rev any higher unless I program twice the amount of gas (6:1 instead of 12:1) and was thinking it might be the magnet. Will check it today.