I expect you have found it by now, but for anyone else wanting a copy of the HP 8970B noise figure meter service manual, there is a copy I stuck here:
**broken link removed**
Feel free to share. I suggest if you have the instrument, or might consider buying one, I'd take it anyway, as I wont be keeping the manual there forever.
As for the original poster also asking about the 8970A service manual, that can be found on the Agilent web site, so there is no need to look too hard to find that.