In addition to what Ukaflyer said (check and meter all the wiring), look specifically at the new fingers on the reverse unit. Almost all replacement fingers are slightly long, requiring the contact tip to be bent back to make contact with the brass inserts on the drum. In the third picture (end on view) the finger on the right looks like it could be too long to hit the contact on the drum.
Was the field winding open circuit that it was replaced? How do you know the armature is good? We always try swapping with a known good armature to verify.
