Got a new battery and it turned over. A few slow cranks and it ran just fine. No noises, no issues. Now it won't start again. Have not replaced the solenoid or coil. The metal ring above the fan like item, which lines up with the coil, is rusty. Could this be the issue?

It sounds like the engine is building too much compression and it cannot turn past the compression stroke. Check and adjust the valves on the engine. If the clearance is off this will create high compression and the backfire issue you are having. Take a look at the link below for assistance with adjusting the valves.

http://www.briggsandstratton.com/us/en/s...

Have you checked to see if your magneto (coil) is sparking the plug properly? Might need the carb taken off and cleaned. Air filter and spark plug been replaced ?

Engine might be done. Maybe not getting enough fuel

I have a four year old Craftsman lawn tractor with this motor. New battery and new starter. The engine slowly cranks one turn and stops. Has also backfired twice. New gas and proper oil level. Something else electrical or just a junk motor? Can turn the engine and it has compression.... not seized up.