If you felt a click 5 or 6 times per crank rotation, it means it's either the pinion or the nylon gear.
You will have to open the drive.
First by removing the chain ring and removing the gear cover : watch this video : https://www.youtube.com/watch?v=S1E45DcEE8w
Inspect the gear teeth on the big and small gear.. see if they are fine.
If they are fine you need to remove the motor from the bike (it's easier if you have a bike repair stand like we have)
Next you need to follow this tutorial :https://electricbike-blog.com/2016/03/02/plastic-gears-suck-replacing-the-nylon-primary-reduction-gear-on-the-bbshd/
Once open, you can rotate the nylon gear without removing the plate covering it. inspect all the teeth, I'm pretty sure you have one that is damaged.
If it's the nylon gear, we will send you one, but to remove it you will need a snap ring plier to remove the snap ring over the nylon gear. something like this : http://www.homedepot.com/p/TEKTON-7-in-Snap-Ring-Pliers-External-3574/207096554