Some of the shift linkages has a threaded end where it screws into a barrel end that is connected to shift arm on the side of the frame where you could remove the hair pin clip on the transmission end and turn the rod to adjust the linkage length. You may not have that adjustable rod because some used a fixed length rod. So the next step is as I suggested and given more information by Startech., but something else to check is to make sure the shift fork isn't bent while you are replacing the gears. It will get bent by customers trying to force it into gear instead of gently trying to shift into gear while slowly letting out on the clutch. Think of the shifting gears inside as trying to mate to half moon pieces together because the is what you are doing.