You can replace the kick start spring by just removing the outer cover and leaving the box in situ...
You can also replace the gear change return springs as well if required any time...
It can be fiddly getting at the fixings holding the outer cover in place that are located behind the forward extension of the inner cover...This is what Hans is referring to I think...
With a standard set up it is frequently necessary to remove the return oil pipe (the outside one) to get at the fasteners...That isn't too messy as there is little oil in that pipe and you don't have to drain the oil tank...Ian