Hello, i repaired a few month ago an old ATV a kymco MXU 250 (2004) is not so difficult, just need some money, manual instruction and some hours.
1) check the noise without the rear wheels and if necessary repair the rear axle on (see video)
2) have good tools and specific grease and a friend to help you maintain the parts, a very good friend 🙂
3) have a bearing puller
have a good trip with your ATV, now new project an old yamaha big bear 350 (1999), all information and advice are welcome 🤗
Thanks a lot