If you want to perform repairs on your own TGB 303R then it will always be a good plan to possess a Workshop Manual to use as personal reference just in case you want to know proven methods to strip off a specific part much like the Brake Pads and install it again appropriately.
TGB 303R Workshop Manuals offers you exact diagnostic details for the car or truck therefore if something is playing up it will help you find out what the situation is and ways to repair it. You can then assess if you can do this yourself or in the event the job is too big you can still make a reservation for your 303R in to a local garage.
TGB 303R manual