starter not engaging flywheel
 

I have a 1994 Chevy Blazer S-10 Tahoe. A couple weeks ago the starter went out so i replaced it myself with a new(remanufactured) starter from O'Reilly's. It started perfectly fine for about a week, until one evening i went out to start it and it wouldn't start. The starter would spin, but it would not engage the flywheel. Then, the very next day it started up just fine. Now it does this all the time, it will start one day, then leave me stranded the next. Some people have told me i might have a bad flywheel, but that didnt make much sense considering it engaged perfectly fine until i replaced the starter. I cant see it being the starter drive either, considering its a new starter. I also had the thought that it might be my ignition switch, i've had trouble with it recently, but im not sure that it would cause this sort of problem. Any ideas and suggestions would be greatly appreciated. Thank you