Hi, i just purchased a second hand Rich bit 350w fat bike. I have a bafang bbshd on my other bike so i know a little about building ebikes. The rich bit needs work,but is running ok. I decided to start with some maintenance,on the hub, greasing cleaning. Watched videos, read loads, and took the 6 screws out of the hub expecting to see 3 white nylon gears but there was a flat metal disc more screws and oil leaking everywhere, the hub has a oil fill hole which has a hex screw. Any help would be appreciated, ive searched for the type of hub motor, but cant find anything like it. All that comes up on Google when i look for oil in hub motor is adding it as a coolant. If anyone could point me in the right direction i would be very grateful. Many thanks.