I found the manual and the parts. Posting some basics here for future ref.
http://www.briggsandstratton.com/mai...S5174_A_LO.pdf
http://www.briggsandstratton.com/mai...44TRI_C_LO.pdf
If your mower is less than 15 years old, there is an excellent chance that if uses an electronic ignition system. These are very reliable as there are no points or condenser to go bad and no need for routine tune-ups.
Testing the magneto
As the magnets spin past the pole pieces of the magneto core, the points are closed and current builds up in the low voltage winding (and flux builds up in the core). At or slightly before Top Dead Center (TDC), the current (and flux) should be maximum and at this instant the points open. The flux then collapses (and the condenser (capacitor) across the points acts as a snubber allowing the current to bypass the open points and preventing arcing at the point contacts). This rapid decrease in flux results in coupling of the stored energy to the turn high voltage winding and results in up to 10,000 V or more at the spark plug.
(For EE types, this is somewhat similar in basic operation to the flyback converter in a switch-mode power supply except that the moving magnet supplies the input power instead of the rectified AC line and the points act as the switch instead of a power transistor.)
The secondary will always be accessible for testing but the primary of an electronic ignition may be not be due to the electronic components:
Secondary: 3 K ohms (maybe a little higher but not open). Much lower would indicate a shorted winding.
Primary (if non-electronic and accessible): very low - guessing less than an ohm.