Safety First! The level of your grinding media in the Vertimill can only be checked when the Vertimill is properly Locked Out / Tagged Out!
This is called the ‘Static Ball Charge Measurement’ in the Vertimill manual. Once the mill is stopped, a calibrated rope with a non-magnetic weight securely fastened at one end can be dropped in the ball charge chute or down the main Vertimill body inspection hatch. (Often the ball charge chute is angled and convoluted so the inspection hatch is more practical.) This ball charge depth is compared to the depth measured when the Vertimill was first commissioned with a new and full ball charge.
See the attached sketch or you can call us for help determining the correct level.
One important side note - if the static ball charge rises by one foot (0.30 m) as compared to when it was first commissioned, in order to maintain the same 80% FLA maximum, your screw liners are worn and require replacement.