Hello! Welcome to justanswer!
It looks like one of the shifter cables is bad. That would cause the sifter to not work right in the gears you listed. I would replace both cables and the hardware with them. See the diagram below for an idea of where the cables go. If the cables look fine and move well and no problem is found then the problem is inside the trans maybe a broken shift fork or bent linkage inside the trans.
CLICK HERE FOR DIAGRAM
Thanks Anthony, that was helpful. Is this an expensive job, parts wise??