Don`t worry!

As long as they`re not worn on the two ends that mate with the gears you can re-assemble the gearbox onto the cassette carrier plate.

Refer to the parts manual if you get stuck.

The selector forks are marked `L` & `R` if I remember rightly. It`s pretty self evident where they go if you take your time & think about it.

Sometimes the rod will stick due to suction caused by oil in the locating hole.
Oil can also cause a springy feeling when re-assembling due to a hydraulic effect as the rod enters the locating hole.

When you are fitting the gearbox back in be aware of the selector drum index roller spring ( No.9 in the diagram). This will get trapped between the carrier plate and crankcases if you don`t lever it into position before you tighten the plate into place.