Got this meter off eBay with the cal button's sticker torn off.

I plugged the probes into the 122 VAC wall, verified by my HP 3468b that is within spec. The Fluke read 133 mV! I tried calibrating ohms and DC volts, that worked well. I get "error 41" when I try to calibrate VAC using the HP as reference. I can calibrate the ohms and VDC just fine, after erasing the calibration. AC voltage remains elusive.

What might be wrong, and what should I do? The self test is fine on the Fluke!

 

Get the instruction manual and start trouble shooting.