Hi John - condolences on your sad loss.
Hmm... you're certainly down but I recall that when my box went back to the menders not only were the numbers down to single figures but the distance was maxing at about 40nm. You still seem to be getting 100+?
If I read you right, you say the supplied aerial is still operating much as it did before? If that's the case and bearing in mind the distance still obtaining, the problem seems more likely to be your main aerial rather than the box.
More checking to be done methinks - anyone in your area who you can take the box to and check it on his system?
If you're not happy though, pack it off to W&S for a fettle. They turn things round very quickly.
Nice to have you back on the board.