There is a washer that sits on the inside end of the axle that holds the sprocket on. If you have a lathe, you can remove the play if its not much.
Remove the wheels and measure the end play, open the chain case and remove the washers and you will see a mark where it touches the axle and the sprocket. Say you have .010” of end float, you need to remove this amount from the inner part up to the section that the sprocket uns up to. Sort of like this profile ------________------- the recess is the part that you need to remove metal from.
I did this on a few 743 machines when i replaced bearings to ensure it was done right.
