Check your pole with an level to make sure that it is still level. Is there a possibility that your pole turned?
How big is the dish and how deep is the pole in the ground, is it concrete in?
It still sounds like it is out of alignment.
If your v-box came with an remote you could swing the dish 1 click at a time to either direction of your programmed position to see if the signal getting better.
Grab your dish at the edge/outer rim and pull or push on the dish so the dish will slightly go up or down and see if the signal gets better, if the signal gets better you may have to adjust the elevation.
Remember KU signal on a C dish is harder to receive, so aim has to be more exact.
You have 2 receivers and 2 dishes, 1 Ku dish and 1 c dish.
Do you use 1 receiver for Ku dish and 1 receiver for c dish since you stated that you have no switch?
You also stated that if you use both receivers that you have a problem with the signal.
Can you tell us more about the setup you have?
What kind of LNB/LNBF on ku and c- dish?
Check 1 dish at a time with 1 receiver and 1 coax cable.
Check your setup in the receiver, make sure it is right.