Sorry if I am not understanding this right but from reading your post, I gather that the starter will spin but the engine wont? If that is correct, make sure that the gear on the starter isn't damaged. If the started gear is good and it has a flywheel. Check the teeth on the flywheel. If they both appear to be in good condition, check to see if the starter gear "meshes" with the flywheel and not butting up against it and free spinning.
If the engine is spinning. Check you sparkplug. Make sure the gap is set and that you are getting spark. If you are not, make sure the the breaker point is set up right. If its like the bolens, they should be preset to a certain amount. If the gap is to large, you wont get spark.
And you could also check your carb. Could be that the carb is clogged and the fuel is staying in the bowel?