Hmm...he also shows no Signal Generator....whatever this kmight be useful for an analyzer...
Haven't got an answer yet from him regarding missing CPU ID.
I believe that the SIG GEN module refers to the module that generates the first local oscillator signal for the first mixer stage. So this module must be present and working if the analyser RF sections can downconvert signals correctly.
This module is probably called SIG GEN because this module is also used in some of Agilent's E443x range of signal generators. So they probably all get called SIG GEN on the production line.
I would also guess that each module has some form of onboard EEPROM chip that holds its module number and name (eg SIG GEN) and serial number. Maybe two of your modules have lost this EEPROM data so they show up as blank entries in the listing?
There does seem to be quite a variation in module types fitted to these analysers. Mine has some modules from the PSA analyser and it also has a different/later RF module to the ones listed here. But it does have the same SIG GEN module that is used for the LO generation.