If you want to conduct fixes on your own KTM EXC 400 then it will always be recommended to have access to a Workshop Manual to keep just for a reference if perhaps you want to know tips on how to remove a certain component for example the Gearbox and install it again perfectly.
KTM EXC 400 Workshop Manuals are able to offer detailed diagnostic info on your car or truck so if something is playing up it helps you identify what the situation is and tips on how to repair it. You can then decide if this can be achieved by yourself or if ever the job is simply too big you could make a reservation for your EXC 400 right into a nearby garage.
KTM EXC 400 manual