Strange measurement error with Datron 1271

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My Datron 1271--the one with the broken right display--has only options for DCV and ohms. That's ok as it is just measuring a 10VDC reference on the 10V range. However, when measuring on the 1V and mV ranges, the display shows 10x too low. It will correctly measure 10VDC on the 1000v but not 100v ranges.
In other words: 10VDC displays as 10.000000 V on the 10V range but displays as 1.000000 V on the 1V range and the 100V range.

Without the information from the right-side display, troubleshooting is difficult.
1) Any clue as to the 10x too low problem?
2) Is there a way to use GPIB for troubleshooting (I haven't found it in the manuals)
Any help will be appreciated.

[Mickle T.]

Most likely the problem is a faulty relay K204/K205 or a lack of control signals for these relays.

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Most likely the problem is a faulty relay K204/K205 or a lack of control signals for these relays.

Yes (thanks too) both relays are clicking when I switch from from one mode to another--hard to tell which ones--K204 and K205 (probably) working. Attached is a better version of the readings obtained in various ranges with 10V, 1V and 100mV inputs. The 'orange' readings may simply be re result of over-voltage? 'Red' = 'BAD'.

JUST BECAUSE A RELAY CLICKS does not confirm signal passage, however. Time to hook up some wires to nearby test points.

BTW: there is a jumper 'A' in the vicinity of the relays; what's up with that? Anyone know?