Druck UPS III Loop Calibrator fault - not measuring inputs

[Greg981]

Hi,

I have a Druck UPS III loop calibrator which will give mA output but reads zer for both current and voltage in.  I've had a look over the boards inside, and not found anything of note, then put it back together making sure that the board to board connectors are fully mated.  Don't know where to go from here.  Has anyone seen this before?  Circuit diagrams?  Any help appreciated, thanks.