If you want to conduct maintenance tasks for your Husqvarna SM 450 R then it is always recommended to own a Workshop Manual to keep just for a reference in case that you need to know tips on how to take off a specific component like the Door and install it again appropriately.
Husqvarna SM 450 R Workshop Manuals gives you certain diagnostic guidelines on your automobile therefore if something is playing up it can help you understand what the situation is and how you can resolve it. After that you can analyse if this can be done by yourself or if the job is too big it is possible to book your SM 450 R in with a nearby car garage.
Husqvarna SM 450 R manual