reset the device, make sure the wires are connected securely, and repeat the calibration procedure. I had a problem like yours, it turned out to be a bad contact in the SMA.
Don't rush to buy spare parts, check the connection, take another wire.
Thank you, Erik.
I'll try to buy an XA17-G4K (or AS179-92LF if that's not available) and replace U22 under the shield.
It looks difficult for my aging eyes, though :-)
