If you want to carry out fixes on your own Vespa GTS 250 IE then it will always be a great idea to have a Workshop Manual to keep just for reference in case that you need to know the best ways to take off a particular part including Door and match it again properly.
Vespa GTS 250 IE Workshop Manuals will give special diagnostic wisdom for the automobile therefore if something is wrong it helps you understand what the issue is and ways to resolve it. Then you are able to determine if this can be done yourself or if the job is simply too big you can book your GTS 250 IE in to a local mechanic.
Vespa GTS 250 IE manual