If you want to do fixes on your Norton Commando 850 Interstate then it will always be a good plan to have a Workshop Manual to keep just for personal reference in case you want to know the way to strip off a certain part like the Brake Discs and install it again perfectly.
Norton Commando 850 Interstate Workshop Manuals can offer you certain diagnostic information with regards to your car or truck therefore if something is broken it can help you understand what the situation is and tips to repair it. You can then analyse if this can be achieved yourself or that the job is simply too big you could make a reservation for your Commando 850 Interstate into a suitable car garage.
Norton Commando 850 Interstate manual