TiminMB,
16 meg off, that seems like a lot to me. Ice mentioned up to 4 Meg, I have observed as much as 5 Meg without trouble, but 16 Meg? That sounds extreme. I would suspect that the internal oscillator of the LNBF is off, but it could just as easily be a similar fault within the receiver, too. Can you borrow the same LNB model from a friend to test? If that is it, a new LNBF would be cheaper than a new receiver. Either way, you will have to isolate it by borrowing or buying one item or the other. Either that, or live with it knowing the offset value and always compensating for it. No money involved there, just an extra step in setup.
Radar