HPS140 appears working, but no trace at all

I have just been given an HPS140 that on first inspection appears to be fully working, however, there is no trace anywhere. I have set the trace to gnd - nothing. I have tried connecting to the calibration point - nothing on auto or manual.

Am I missing something, or is it faulty?

UPDATE:- after searching the net for clues, I discovered that holding the menu key down whilst turning the unit on puts it into calibration mode. This results in ā€œ1-Pos2 ADJUST CV2 FAIL ???.??Vā€ at the bottom of the screen.