*First I would check the coax connections to make sure they didn't loosen vibrating in the wind. You might get lucky and that's all that happened.
If after verifying the dish has not moved on the pole... as others suggested:
Wind whipping dish up and down could throw the feed out of center, especially on a button-hook dish. Could even warp the dish. (less likely)
Wind blowing on a dish can cause static electricity to build up. My VBox positioners have lost the correct location for each sat after a wind event. Usually only a few clicks either way re-peaks signal. But I have rarely had the boxes completely lose memory for all positions. Either way, just had to reset all positions correctly. I expect you have already tried this.
I had a dish tracking as best as I could, from 55.5 to 135 West, although I suspected that there was room for improvement on furthest east satellites such as 55.5 and 58 West. Winter arrived before I could make further adjustments, so I tolerated what I had. After some serious windstorms several weeks in a row, it started getting worse, and on the first day above freezing, I took a closer inspection at the dish. First fix was to re-tighten the mount as well as hardware on both ends of the linear actuator. Then call up east and west end of the arc, writing down Quality readings on several satellites. Compare position numbers on the motor control with previous settings and write them down. Next was to go to my due south satellite and adjust the elevation for peak quality reading on an active signal. Mine was almost 3/4 degree off. Then call up strategically separated satellites in extreme east and west to check signals again.
Check position numbers as well as Quality readings to see if there is a major change anywhere. In my case, it was dead on for the mount being centered at due south. My elevation might have been off a quarter of a degree with initial setup, as viewed from due south satellite. The after-adjustment results were greatly improved readings on both ends of the arc as well as at due south, which matched the drawings you have been given. If there was still room for improvement on either east or west end of the arc, then you should push the reflector up and down to see if it gets better on either end. If the eastern arc gets better when you push to a lower elevation, it means that the mount needs to go a little bit west. Always re-check due south quality reading after making mount east/west adjustments.
Repeating some cardinal rules for aligning a polar mount. Do the alignment in this order:
Get the declination set (angle difference between the mount and the back of the reflector elevation), using a digital angle finder (inclinometer), while at due south or center of the arc. Get it within 0.1 degrees, which can be done with inexpensive ($25 to $40 typical cost) devices from Harbor Freight. Once you have this set it place, do not adjust it again.
Set the elevation for best signal at due south. Do not adjust elevation again unless it is at due south during a recheck.
Check quality readings on furthest east and furthest west receivable satellite. Test by gently raising or lowering bottom of reflector at center, to determine whether mount needs to go east or west. Move the setting clockwise or CCW in baby steps of no more than a degree or two.
Always go back to due south to reconfirm its quality reading. Elevation adjustments should only be done at due south. Check east and west reception again until you are happy with the results.
