If you wish to do maintenance for your TGB F409 125 then it is usually recommended to possess a Workshop Manual to use as a reference in case you need to know the best ways to remove a particular component for example the Drive Shaft and fit it again perfectly.
TGB F409 125 Workshop Manuals can provide detailed diagnostic details with regards to your car so if something is not working it will help you work out what the problem is and tips to fix it. You will be able to analyse if you can do this on your own or in case the job is just too big you can make a booking for your F409 125 in to a local friendly mechanic.
TGB F409 125 manual