This procedure covers how to measure the oil level and fill the cambox of a side-mount tool changer (SMTC) on a vertical mill.
Vertical mill SMTC camboxes will have either a sight glass  or will have an oil-level plug . The oil-level sight glass and the oil-level plug are in the same location on the SMTC cambox. However, the most effective way to check the oil level is with a dipstick .
The recommended oil level has been raised, and 4 inch (101 mm) from the top surface of the cambox is currently recommended for all vertical camboxes no matter when it was manufactured. This is higher than the sight glass and the oil level plug, so these are no longer recommended to use for checking oil level.
Important: If a cambox's oil level is not at the correct height that may not indicate that the cambox is leaking. Over time the cambox will slowly lose oil or the cambox may have been filled to lower oil level previously. Before replacing the cambox do more investigation to see if the cambox has been damaged and is leaking.