I had a similar issue the other week took down a 1.1m triax with motec 2100 diseqc motor, and replaced it with a channel master 1.2m with polar mount and 18" actuator.

I had the pole 100% vertical in all directions, I could find 4.8e, 7e, 9e, 10e, 13e no probs (didn't bother looking further east), but I couldn't for the life of me find 0.8w.

I could even get 5w, 7w and 8w but nothing from 0.8w.

Eventually I figured that the elevation of the dish had to be out a little, so I gave the elevation a tweak (sorry can't for the life of me remember if I needed to go up or down) but it was around 1 maybe 1.5mm out, as soon as I tweaked it 0.8w came beaming in with around 90% signal on the telnor test card channel (btv-1/swedbank).