Possible dish alignment problem?

[dalk1]

Hi, can someone help confirm this weird problem before I climb a ladder?

When I take my f5s to my parents house (former sky subscribers until 2005) about 30% of the channels in the favorites have no signal, however if I do a blind scan I can find all the channels working in different locations. Back at my house all the favourite channel lists are fine.

Does this mean my parents dish is slightly misaligned or is there another explanation for this?

Thanks