If you choose to execute maintenance on your own Polini Minicross X3 R then it is always a good idea to have access to a Workshop Manual to keep just for reference in case you need to know methods to remove a particular component for instance the Door and install it again appropriately.
Polini Minicross X3 R Workshop Manuals will give identifiable diagnostic details for your vehicle therefore if something is wrong it can help you find out what the situation is and the way to repair it. Then you are able to analyse if this can be done by yourself or if the job is just too big you can actually make a booking for your Minicross X3 R in with a decent garage.
Polini Minicross X3 R manual