[Test-Equipment] HP 141T spectrum analyzer question

[greg mijal]

Hi all:

I have a problem with my HP 141t spectrum analyzer and I can use your
expertise to help get it back into good health again.

Here's the problem:

The analyzer sweeps and has sensitivity.  However,  the straight line
trace at the bottom of the screen is no longer flat.  It has a series of
bumps in it and they walk accross the screen while the analyzer is
scanning.  If I insert the 30 mhz cal signal into the main input, the
bumps keep walking thru the trace, up, over and down the cal signal too.
The "walking bumps" also seem to cause the displayed cal signal to
jitter.  I looked at the vertical output bnc of the analyzer with an
oscilloscope and there is no sign of the bumps but the cal signal is
jittering along with the main trace.  I have manuals for all
sub-assemblys and can follow along with your advice.
I think I have a problem with the display unit.
Any advice out there?
Thanks!!

Greg
in sunny Feenix