Just because the battery is fully charged dosent mean it will crank the engine over....put a volt meter on the battery...and see what the voltage drops to when cranking...i am guessing it will drop to well below ten volts...the battery needs replaced...i would also check and do a voltage drop test across all heavy cables from the battery to the started....there could be corrosion inside the cable causing a significant voltage drop....another possibility is that the engine is bad and bound up not letting the started turn it...can you crank the engine over by hand freely with a breaker bar and a socket on the harmonic balance/crankshaft bolt...???? And just because a starter was rebuilt dosent mean it was rebuilt RIGHT....did they install new brushes...bearings and check the commutator for shorts and opens? How about the starter solenoid....????