If you have to execute maintenance on your Suzuki GN 125 then it will always be recommended to possess a Workshop Manual to use as reference if you want to know the best way to take out a certain component for instance the Wheel Bearing and fit it again the right way.
Suzuki GN 125 Workshop Manuals offers clear distinct diagnostic wisdom for the automobile so if something is faulty it will help you figure out what the problem is and methods to correct it. You will be able to evaluate if this can be achieved yourself or in case the job is simply too big you can actually make a reservation for your GN 125 in to a suitable garage.
Suzuki GN 125 manual