65 to 70 % sounds low if you are talking about bbc and you are in the uk. I'd also say the dish may be out of alignment. It could be a duff lnb, or it could also be that you have something like a tree or bush or roof slightly in the way, or may need a larger dish for some reason. Having low signal to start means that when it rains and drops even lower it isn't enough signal to work.
ive sorted it now basicly i changed the lnb and that raised my signal a little bit.
anyway the guy where i bought it from said that he's had a few problems with the same dish (triax 88cm ) he told me to put abit cardboard under the arm that holds the lnb and it should be ok ,he was rite
Question has anyone else had problems with this dish or could it be a manufacturing problem