I'm not familiar with that machine.. but ditto what toad said.
Most boxes have a stud to let you adjust steering sector gear backlash.
This isn't always the source of play though, as thrust bearing wear also introduces play.
I'd try the unoficial allsi site.. lots of info there for the orange tractors.. plus places to buy parts.
YT has some orange parts as well.
hit the discussion forum at the AC site.. post away.. you are sure to get replies pretty fast..
Unofficial Allis Home Page
Soundguy