Tractor Repair: Allis Chalmers WD 45 gets stuck in gear, allis chalmers wd 45, allis chalmers wd

Question
I have a Allis Chalmers WD 45 tractor that frequently gets stuck in first gear.  I have to take the shift lever out and realign the gears or the shift forks using a screw driver and then put it back together.  Is this a common problem and is it a costly or difficult fix.  I'm not sure how much money I want to put into this.  Any help or feed back would be great.  Thank you!

Answer
  From what I have heard, this is a fairly common problem with these old Allis Chalmers models.  That and jumping out of gear.  The bottom of the shift lever and the shift rails are probably worn enough that the bottom of the lever can slip between the rails.  There is no way for me to estimate what it will cost to fix.  It depends on where you have it done and where the parts will come from.  I have fixed old Farmall tractors by building up the bottom of the shift lever where it's worn with a welder and grinding it to fit.