If you have to carry out maintenance on your Yamaha XS 400 SE then it will always be recommended to have a Workshop Manual to keep just for a reference in the event you want to know ways to take out a particular component for example, the Door and install it again in the correct way.
Yamaha XS 400 SE Workshop Manuals are able to offer specific diagnostic info for your car or truck therefore if something is playing up it will help you work out what the situation is and some ways to correct it. Then you are able to analyse if this can be achieved on your own or if ever the job is too big you could make a reservation for your XS 400 SE into a trusted car garage.
Yamaha XS 400 SE manual