You could have a bad solenoid so jump across the top to energize the starter. If that doesn't work I'd remove the spark plugs and energize the starter again. Try rotating the crankshaft by hand next then check for something in the impeller if the crank doesn't move easily. You want to verify the starter is the culprit. If the starter is OEM a rebuild kit is the best way to go. I generally just replace the brushes, clean the inside of the starter, clean the armature, etc... make sure you seal it good when you're done. Good Luck !!