If you want to accomplish maintenance for your KTM 400 EXC then it is usually a great idea to have access to a Workshop Manual for personal reference in case that you want to know easy methods to remove a particular part such as the Brake Pads and fit it again the right way.
KTM 400 EXC Workshop Manuals will give certain diagnostic info with regards to your car therefore if something is broken it will help you determine what the issue is and easy methods to correct it. You will be able to analyse if this can be achieved yourself or in case the job is just too big you are able to book your 400 EXC right into a local friendly mechanic.
KTM 400 EXC manual