Since we bought our house, we've been using the previous owners' Sky dish to get Freeview. Thanks to Wellington hilliness, the dish is up the hill on our garage, so there's a fair length cable run, and a 20db amplifier in line with the satellite box (a DishTV S7070R).

We've been losing signal in heavy rain more and more lately (to the point of TV being unwatchable) and having read that some of the sky supplied LNBs are beginning to show their age, I ordered this kit:

http://www.dishtv.co.nz/LNBs-Dish-Mounts/141-11300-LNB-Holder-DIY-Pack/flypage_images.tpl.htm

to replace the sky LNB (which is a Sharp dual throat one with 4 outputs).

I'm now wondering whether I've messed up by ordering the 11300 LNB, rather than a 10750, because the instructions for the satellite finder tell me to check the signal with the satellite box tuned to a channel - will this work if the box has been tuned using the old LNB frequency of 10750?

I also tried to get things working by just fitting the new LNB with the same skew as the old one and doing a blind scan, but I can't get even a hint of signal doing that. I've never tried satellite installation before - is the precision needed so high that I can expect absolutely zero signal with the new LNB unless the alignment is perfect?

I've now given up for the weekend and reattached the old LNB, which without any fine-tuning immediately pulled in an 80% signal, so there's obviously something wrong in the way I'm trying to fit the new LNB.

Can anyone point out where I might be going wrong?

Mark