extended loss of 1 satellite- signal

I have a Sony T-60, and it's been doing well for quite some time. It's hooked up to 2x4 mutliswitch which in turn is hooked up to an 18" dish w/ dual LNB.

Lately, we've been seeing to symptoms that I assume are the same problem. Numerous programs that are "way shorter than they should be", and frequently while we're watch we get the magical "Search for signal on Satellite 2". This signal will hang on the screen for hours at a time. There are no storms nearby, and I believe my view to the satellite is unobstructed (plus, it's always #2).

I've checked my connections and I swapped the two inputs at the multi-switch (the problem continues on Sat#2).

So, the question is, which component is most likely the problem? Are there any other diagnostic steps I can take before buying replacement equipment?

Thank,
David