If you choose to perform repairs on your Yamaha TRX 850 then it will always be a great idea to have a Workshop Manual to use as personal reference should you want to know simple methods to take out a particular part including Gearbox and fit it again efficiently.
Yamaha TRX 850 Workshop Manuals can provide particular diagnostic information with regards to your vehicle therefore if something is broken it can help you work out what the issue is and some ways to fix it. After that you can decide if you can do this on your own or that the job is simply too big you can actually make a booking for your TRX 850 in to a nearby repair garage.
Yamaha TRX 850 manual