Mancini transmission

Bought a 727 from Mancini 8 yrs ago with a forward manual valve body, and a bolt in spraig. Was supposed to have been built by Ron Mancini. Eight years later we just installed it. First gear worked fine the 7 blocks home. Later that evening tried it, and no wouldn't go in first. This morning first was there. Thought shifter needed adjusting. Nope. Any Ideas? Thanks in advance for any help.