Any way to tweak the tuning of particular channels on a dbox2

I have a sagem dbox 2 and only really have trouble with a few channels. I downloaded sporster 1.7 1x and have the irish cables.xml and the dublin service.xml. The main channel I have trouble with is TV3. If many people on the road are tuned into the same station does this affect my signal strength? I remember years back people had a few TVs with cheap splitters and when 2 people watched the same station in the house the reception would be poor? is this the same effect? since it does only seem to happen when more popular programs are on?

Can I tweak the settings on one channel, without doing a entire rescan. Or would changing to commando make a difference? my signal strength is usually 2500-2600.

Also is there a PDF manual for the sagem dbox2?

 

Backup your services.xml and do a slow scan via cable Dublin and the option keep bouquets.