[Test-Equipment] Need help on HP-8970A

[Ed White WA3BZT]

Hi Gang:
Need help to figure out what is going on with a HP-8970A Noise Figure 
Meter and Noise head
When I turn on the meter with the head connected to the input and power 
I see the following
All lights lite test
4 dashes then E 26
I then key in 33.0 and press the  Special function
I get 4 dashes then E 13
The noise head is a Noise Com NC3108 (opt 4 [ 28 VDC])
What do I need to do to fix this problem
The unit worked before I received it (Trusted friend) and we are 
wondering if something happen in shipping. I have looked at all the 
boards nothing out of place everything seams to be there.

Any help for the users of the noise meter will be a great help
Ed
WA3BZT