jonesy, I think it is rare for Briggs alternators to fail, but quite common for the diode in the output lead (just near the connector at the free end) to fail. If you have a voltmeter, just disconnect the Briggs engine's charging wire at the plastic connector where it attaches to the ride-on's wiring harness. Probe the engine lead on the upstream side of the diode with the engine running and see if you detect AC voltage. If you have AC upstream of the diode, chances are the alternator is OK. Then connect a DC ammeter on 10 amp range between the engine's charging wire and the ride-on's wiring harness. Start the engine and see if there is current passing through from the engine to the mower's harness. Remember, you will probably only see 2 Amps with the engine at maximum speed, depending which model alternator you have. Most of them are only rated at 2-3 Amps.
