Bill,

 There are two reasons I know cause this problem:
 -shift guides are worn, but I don't think so;
 -clamps on the shift rod is loose, I found that on two
of four old  Vanagons: The shift rod comes in two
pieces, divided just behind the gasoline tank. To
fix the problem turn the rods against each other
only a little bit until rear and first gear will shift in
easily. Tighten the clamp. If this problem comes
worth, the first gear shifts in only by pushing down
the gearlever (like on rear).

Helmut
'80 Camper