Calibration of MKS Vacuum Gauges(Model: 116A)

Hi All,

I am wondering if anyone has a user manual in your group or knows to
calibrate MKS Vacuum Gauge. The model in our lab is TYPE 116A
baratron, which is probably the first generation product of this
manufacturer, MKS. It is too old to find calibration information
online. If you happen to know how to calibrate it, please let me know.
Your help is really appreciated.

Best,
Henry