Hardinge CHNC II+ lube system

I have been working with a customer's 1986-1987 CHNC II+, and am trying to help him understand the axis lube system.

There is the usual air-pressurized way lube tank under the left end of the apron panel. His machine manual says that tank lubricates the "carriage and cross slide ways, cross slide ball screw, vertical slide ways, collet closer and part chute".

There is also a filler cap on the front face of the cross slide, with a placard advising it should be filled with Vactra #2. This appears to lead to the turret components.

Finally, there is a sight glass on the front of the Z axis ballnut block, also with a placard advising it should be filled with Vactra #2. However, it is not immediately obvious where this reservoir is filled from. The machine manual indicates a filler plug above the telescoping ballscrew cover on the left side of the ballnut block, but this machine has no such plug.

If you have a machine like this, do you know where the filler for Z axis ballnut lube is located?

The sight glass is visible in the attached picture. The picture is, unfortunately, more focused on the X axis limit and home switch assembly....