I got my hisun 550 back, royal king had it for a month. Replaced drive shaft sleeve and rear drive shaft connecting seat. Which mine had a spring behind the nut and washer that screwed to the pinion gear. I called hisun and asked them about that compression spring in there and they told the mechanic to put it back in. So I got it home and called the motorcycle doctor and he told me there was not supposed to be a spring in there. The mechanic at Royal King told me he put it back in, so I took it all apart and the spring was not in there after he told me he put it in. Could of saved me 4 hours taken it apart and putting it back together. I wouldn't let royal king work on my utv ever again even tho it's still under warranty. Here's pictures how it was put together. At least I know now my bolts are all tight.