I bought a Pace 2600 from the wonderful e-bay that supposedly would not update.:mad: Mind you it only cost me £35
After several attempts (AT LEAST 20) I hooked up the box on the shortest patch lead I could get away with (about 2 meters direct from the lnb with the box ballanced on a window sill). This improved the signal strength and quality and the box then updated on the first attempt.
It would seem you need a very strong, high quality signal to get these boxes to update these days. I can't explain this but it worked for me.;)