Sony HTP-1100 - snake's wedding

Just bought one of these (£220 from dabs) and am very pleased with it.
Being old and deaf, I don't really notice that it isn't really hi-fi!

I have connected it up as follows:
Sony TV KV-28DX20U with 3 scart inputs, from:
Sony VCR SLV-SE710
Sony DVD NVP-NS330
Pace box for tnl cable

As can be imagined, there is the mother of all snakes weddings behind
the TV! This all seems to work OK, except one area, which is the VCR.
When I have used the cable box or DVD and then change to the VCR, the
system won't give me any sound from the sound amp.

Can anyone advise me the optimum way to string this lot together?

Cheers,
Peter