If you want to do maintenance on your own Veli VL150 6 then it will always be a good plan to have a Workshop Manual to use as personal reference if you need to know ways to remove a specific part for example Brake Pads and fit it again safely.
Veli VL150 6 Workshop Manuals will give you special diagnostic guidelines on your car therefore if something is faulty it can help you work out what the issue is and tips on how to resolve it. Then you are able to decide if you can do this yourself or if ever the job is too big you are able to book your VL150 6 in to a trusted mechanic.
Veli VL150 6 manual