Before you toss the old one, pull the flywheel and check all the magnets are there.
Check there is no magnetic dust / gravel etc between the magnets as these effectively short out the small magnets and make 1 big magnet which drastically reduces out put.
Then check the ground connection of the stator.
One ( or more ) of the mounting bolts will have a wire from the coil under it.
Give it a good clean up if there is any corrosion or the bolt is loose.
Ideally you need to see 27V AC minimum from the stator and most manuals tell you to toss them at anything under 30 V AC as you loose a little voltage during the conversion to DC
X volts AC = x/2 Volts DC.
The stator is paired with the rectifier so if you upgrade you need to replace the rectifier as well.
Check the Yellow pages for a mower REPAIR shop in your area.
We all end up with boxes full of stators & rectifiers from engines that throw rods or seize.
Take your old one with you.
Briggs kept consistent mounting centeres for their stators so you have a lot to choose from.
make sure you tell the shop you have an electric PTO.
FWIW the colour,shape & number of the wires and the colour & shape of the plug codes out Briggs stators.
If you want a new, exact replacement , make sure that the new one has the same wires & plug ( including colour ) as the old one.