Flywheel magnet came loose

Remove flywheel and check the 4 magnets are still glued in place on the inside of the flywheel. If any of the magnets are loose or two are unglued from the flywheel the voltage will only be slightly above 12v
instead of closer to 14 something volts. The magnets will still be inside and maybe stuck to the coils. Re-glue with JB weld or similar type of two part epoxy. Magnets should be glued around the inside of the flywheel-equally spaced with alternating polarities.

Could be a bad alternator or battery

You will probably need to remove the engine covers and check the "air-gap" between the coil (ignition module) and the magnets in the flywheel. An acceptable gap is .010"-.012". This is about the equivalent of the thickness of a standard business card. Once you are to the point of adjustment, fold the business card in half (with coil module screws loose, but still in engine), slide the card in between the flywheel and pickup legs on the coil; then turn the flywheel until the magnets line up and let them "draw" the coil in with the folded up card in between. I say fold it, because the pressure from the pull of the magnets actually compresses the paper card, and you end up with an acceptable "air-gap". Tighten the module screws real tight while the card is still in, them remove the card. Try this and post back if needed. You can initially check the "air-gap" with a feeler gauge, but it is tricky with a steel one as it tends to stick to the magnets. They have non-magnetic gauges for this.

is it electric start or manual pull?? remove pulg and see if it cranks over. Could be mouse nest under recoil cover or under flywheel, could be rusted to the magnets. need more info. Oh yea make sure belts are not holding you back remove them or make sure they are loose.

what is going on with the magnets on flywheel or are you talking about the magneto ( coil)

there should be about 3 screws that hold the screen over the flywheel. If you have a compact wrench it is the easiest way to remove the flywheel. Remove the nut and using a fly wheel puller, which can be made with a few screws and a piece of 2" x 4 " metal with drilled holes the exact distance of the flywheel puller holes in your tiller (much cheaper than purcasing one), work the flywheel loose and ta da there is the magnet.

There is a magnet on the above the flywheel that creates spark. It is called the armature. This will allow you to get spark as long as your flywheel is good, but this is the most common cause besides electric start system