Alot of times it can be the armator plate that has worn grooves in it. Usally you can use fine sandpaper to remove the blemishes and that has worked in many situation. or new plates are 15.00.

 

Thanks guys I just went through the thread on the highlifter forum, great info.
Here are the part numbers from John Deere for a front diff rebuild

seal kit MIA10654
A-plate MIA 10656
roller kit MIA 10666
cage kit MIA10667