Start at the transmission. Move both levers back and forth and leave both levers in the middle position (neutral). Now look at the shifter box. The Paws/Forks should be perfectly aligned (neutral). If not adjust rods to transmission until the paws in shifter box are perfectly aligned. This is all the adjustments you can make. If the shifter still does not work properly then you have other problems, worn parts, bushings, broken spring, etc.
RdsLessTaken/Don

Start At The Transmission; put both levers in middle position:
http://i1291.photobucket.com/albums...unning%20Boards/IMG_2704_zpscb1dbb8d.jpg

Check Shifter Box For Perfect Paw Alignment:
http://i1291.photobucket.com/albums...nning%20Boards/IMG_80142_zps5e9171f5.jpg