I have posted a document discussing the spurs that Jurgen has reported, and that others might experience at various levels:
I call these LO1 Leakage Spurs. Perhaps Mixer 1 Leakage Spurs would be a better term (because LO1 can also leak in other ways), and some might prefer the term crosstalk rather than leakage.
The document discusses the underlying mechanism, and identifies the specific frequencies involved (elaborating on Scotty's comments). We have not yet resolved the source of Jurgen's unusually high spurs, but the current suspect is the tuning of the cavity filter.
In short, if you have a spur at frequency Fspur, your final IF frequency is IF2, and Fspur differs from IF2 by IF2/N for some reasonably small integer N, then you have one of these spurs. They are all at or below 2*IF2. If you zoom in on the spur, you will see that, while a normal signal shows up with a width approximately equal to your RBW, the spur will have a width of RBW/N.
I have also created a folder called SamW Files, and moved most of my files there, to reduce file sprawl. Some file links from older messages thus may not work. I did not move the Minicircuits quotes or the current beta of the MSA software.