Air and Lube Error on a12_15 CMM

z-counter balance pressure would be my guess at this point.

What is your source of compressed air? You could legit have fluctuating compressed air that your regulated supply to the cmm results in under-pressure situations (most cmm's produce an "Air lube fault" when supplied pressure drops below ~58psi (4bar)), even if it's an instantaneous drop.

If you have consistent and non-fluctuating supply air pressure, you could have a few other issues:

1. As mentioned above, your z axis counterbalance isn't adjusted adequately. if you don't have an exposed knob on/near the top right corner of your X axis bridge, it's under the rightmost cover of your bridge.

2: Your cmm has two air pressure sensors, typically located near the air inlet, up in the Y Axis faring's. One that's labeled PCC and one that's labeled PAP.
- PCC is the Z axis counterbalance regulated pressure sensor, and the
- PAP is the supply pressure, both from the supply and the air bearings (in an open-loop to make sure you don't have a blown air line to a bearing).
--one of those sensors could be failing, or you might have excessive amounts of air leaking from someplace.

3. Your solenoid valve, which electronically actuates upon machine start, when the PCC (z axis pressure) is sufficient, could be sticking of faulty. There's a shiny machined ring around a black rubberized bypass button at the top of this valve, to manually switch on air supply if it's sticking or faulty. it's located directly above the air inlet filters/regulator of the machine, inside the Y axis faring's. When this solenoid valve is functioning & open, you will see an orange led light glowing at the connector.

Here's a word doc a got from an FSE, explaining the entire pneumatic system & how to set the PCC and PAP values.
Hopefully it helps.