If you need to undertake fixes on your TGB 303R 150 then it is usually a good idea to possess a Workshop Manual to use as a guide should you want to know how to take off a particular part much like the Dashboard and match it again properly.
TGB 303R 150 Workshop Manuals provides particular diagnostic details on your car therefore if something is broken it can help you find out what the situation is and ways to fix it. You will be able to evaluate if this can be done yourself or if the job is too big you could book your 303R 150 in to a trusted repair garage.
TGB 303R 150 manual