the picture via Rf is clear as a bell - no snow or noise.
As regards to what I've tried so far...I've tried new images(Sportster_1.76.3_2xI, Cryo_sportster17_2x_uk04 and Gavs newest image) old images(boxcracker 3.5), I've removed the modem, I've tried feeding the dbox from my cablemodem line(I currently take analogue basic and BB fron N*L). I've tried the appropriate services.xml for my area(Glasgow south) and also normal scan and bruteforce scans. The net result is that with most of these images I can find 29 transponders but no channels.
BER is 20-2600
SNR is 41000-52000
SIG is usually approx the same as SNR
I've not had a sniff of a TV picture coming through scart and just about ready to give this up and take up performing open heart surgery(less stressful and less complicated).
(having a beer in the last chance saloon)