Okay, I pulled it back apart and checked the screens that you mentioned David. They appeared to be pretty clean, but I went ahead and washed them along with the little valve body piece and the intermediate plate. Everything is spic and span clean. I'm heading out to the parts store right after the Miami game to buy more ATF. I'll report the results afterward.

Update: Not knowing what the problem might have been with the other valve body, I put the original back in. I have forward (2nd) and reverse gears back now, but it won't upshift at all. I'm getting a little frustrated at this point. Any ideas on what my next plan of attack should be?... Anyone?