The sprag clutch is a one way bearing in the tsdz2 ebike torque sensing motor that transfers your pedal torque to the main gear which is attached to the chain ring. After 2500km of hard ri ding this gear began slipping under high load. It slips whether the motor is on or off. There is less slip when you are using full turbo assist because you don’t need to put as much pressure on the pedals. It got so bad that it was getting really hard to go up hill. I purchased the replacement gear from eBay for only $15 AUS delivered, hopefully it lasts longer than the original.
At only 1380kms I changed the blue gear with a brass one. So far both repairs have been really easy to do. The motor is ideal for mountain bike riding and I have no problem recommending it.
See my video on Servicing the motor and replacing blue gear.
Also check out my video on the sprag clutch slipping.