Okay well antennas seem to be far enough ahead to not be bothered from the hopper tops.
DOP is the Dilution Of Precision, higher that value, the less accurate it will be. Basically the reason that value will be higher is because of obstacles in the way ( hopper topper, trees, buildings, etc)
But in a wide open field you should be fine, but it is located on the info screen where you go to see how many acres you have done. might be listed as HDOP.
Okay I think the stock settings for minimum satellites is 7, or maybe 6, been a long time since I always changed ours. Either way sounds like it isnt catching onto enough satellites, ours usually hit 10 or 11 I think by mid day. Remember the more satellites it can lock onto, the better your pass to pass accuracy will be.
I got rained out today, and have a trimble 500 in one combine in the yard, so I will play around with it and try and remember what I did to improve ours a bit, and I will get back to you if no one else has chimed in.