Missing 3rd on 904 trans

Update: I pulled the valve body and just as everyone guessed there was a ton of crud built up in it. Cleaned everything out and did a transgo stage 1 shift kit while I was in there. Just got it all back together and took it around the block. Reverse, neutral and 1st all work great. Unfortunately it won't shift out of first automatically or manually. I'm going to wait for it to cool down and pull the pan and valve body back off and see what I can see. Also I ordered that Tom hand torqueflite book and it'll be here Monday.

Something like this was the exact reason I was afraid to mess with the valve body when I had it apart for the clutches and I guess it became a self fulfilling prophecy. Such is life.