Agilent Technologies ESA Series User's/Programmer's Reference page 138

Front-Panel Key Reference
Source
peak. For the best measurement accuracy, a tracking peak should be
done whenever you reduce the analyzer RBW (especially if the
amplitude decreases).
Key Access:
Agilent E4402B, E4403B, E4404B, E4405B, E4407B, and E4408B only.
Man Track Adj
Allows you to adjust the frequency of the tracking generator oscillator
manually using the step keys, knob, or numeric keypad. The tracking
adjust is tuned to maximize the amplitude of the trace.
Key Access:
When
NOTE
When the resolution bandwidth is < 1 kHz,
on.
138
,
Source More
,
Source More
is On, resolution bandwidths < 1 kHz are not available.
Source
may not be turned
Source
Chapter 2