[wejones]

I've had LNBs last for 10 yrs and had them last for only 1 month, but I've never had an lnb "get weak". The ones I've had go bad (1) suddenly changed LO freq by 20 MHz, (2) died completely (3) developed birdie freqs that would wipe out reception at certain temps. I'd suspect the moisture or alignment issues mentioned by Rainman. Try substituting coax with a short temporary section to rule out bad coax. Also, I assume this is obvious, but there haven't been any trees growing limbs above your dish, blocking your signal have there? I know that the trees have been closing in around my dishes, some from above, and offset dishes aim higher than they appear to be aimed, so you might think you have a clear view when you don't.