How I wish I had a crystal ball to answer your question. But anyways will try. So many factors influence the SQ after an install. Even the same installer , using the same equipment, the same day might not get the same results. Maybe you did not aligned the dish optimally the first time. TP's could fail and loose power or SAT operators could decide to make changes to it to adjust it for some reason. The problem is , that it is not clear to me if you are using the same Dish size.

Apparently from both of your threads, you started with a big 1.2 m Dish and then a smaller 39" so therefore this could account for the lower signal level. Those are C Band so if you get them with a 39' then enjoy being lucky enough, most C band TP's do not even work with even a 1.2 meter.

Even 63, on a viewsat for instance, is well above thereshold therefore you will not have problems in the future either.