1996 Honda trx 300 fourtrax left side engine case !

Here is the problem i had a left hand side engine crank case cracked and was leaking oil this was a running rideable 4 wheeler until i cracked case!
now sence changing the case and transferring all gears shift drum and all,no matter how i position gears washers and completeing following the repair and service manuals on placement of gear and mic the washers and all! no matter i can get it to change gears properly it either locks just like park or will only change a couple gears and then lock! please help!!!!!!!!!!!!!