If you need to carry out maintenance on your own BMW R 90 S then it is always a good plan to have a Workshop Manual to use as a guide if you want to know easy methods to take off a specific component for instance the Door and fit it again perfectly.
BMW R 90 S Workshop Manuals will give you exact diagnostic details for your car or truck so if something is playing up it helps you work out what the issue is and the best way to correct it. Then you are able to assess if this can be achieved by yourself or that the job is simply too big you can actually make a booking for your R 90 S into a suitable car garage.
BMW R 90 S manual