If you wish to do adjustments on your BSA A 75 Rocket 3 then it will always be a great idea to own a Workshop Manual to keep just for reference if you need to know the way to remove a certain component such as the Brake Discs and fit it again safely.
BSA A 75 Rocket 3 Workshop Manuals offers you detailed diagnostic details on your car so if something is playing up it helps you work out what the issue is and ways to resolve it. You can then decide if this can be achieved yourself or if ever the job is just too big you could make a reservation for your A 75 Rocket 3 into a local friendly mechanic.
BSA A 75 Rocket 3 manual