Thank you for your insights into this problem. Just to answer a few of your questions:
It has been this way since
installation. Sometimes worse than others but does not correlate to anything (cloud cover, wind, time of day, etc.). A factory reset seemed to help the first time I tried it 6 weeks ago. It worked for a few weeks then got bad again. Tried a factory reset again recently and no improvement this time.
System has been up since August 2007.
Purchased system Summer of 2007.
I don't have spare equipment.
I did not have the problem with the short piece of coax out at the dish but when I brought the receiver inside I did not have the problem inside either. So this was inconclusive. Also, the signal strength and quality were within a couple percent between long and short coax.
It sounds like it could be software but with that said I agree the right way to trouble shoot this is to swap out components. Since I don't have spares I think updating software is probably cheaper and easier than throwing other parts at it.