Why can't my droid incredible find system updates?

I got my phone when it first came out, used it normally, upgraded to froyo, then decided to root. I had no problems for months. Recently, I decided to un-root my phone using the method described here: http://www.droidforums.net/forum/droid-incredible-hacks/51134-video-howto-unroot-incredible-downgrading.html to remove clockwork mod and such. It went back to "factory defaults" and everything works fine, except that it can't seem to find updates. It syncs, updates apps and everything just fine, but as far as system updates, it is perpetually "Up to date." I have tried to factory reset from the phone twice, which works as it should, but the problem remains. I really miss the features from froyo, and in general just want my phone back in working order. Any help would be greatly appreciated, thank you!