Base on my last record, it can easily grind 10 kilograms cocoa nibs for 40 minutes. It is very fine and second pass is almost not needed. Then, why was the grinder seemed taking a hard time. I was exactly doing the same procedure as before. It took me twice longer to finish the same batch quantity. Something must be terribly wrong.
For cleaning, I usually let several batches of water circulate for several minutes until the water is visibly clear. I took off all the parts this time for general cleaning and perhaps see if there was something wrong with the mill. I was surprised I saw a hardened cocoa underside the rotor and between the rotor and shafting. This must be it, it was creating friction making the motor to lower its speed, and even slower to the point it stopped when nibs were added in hopper.