I bought a Chinese valve amp (Yaoin 300B job), on Ebay. Like this one:

http://cgi.ebay.co.uk/300B-High-End-...QQcmdZViewItem

It worked great for quite a while and I enjoyed the sound.
Now the left channel has gone dodgy. The music is still barely "there", but
all scratchy and weak. The right channel is fine.
I've swapped leads and connectors to establish that the speakers/cables/CD
player are not at fault. It definitely seems to be the amplifier. The left
output valve doesn't get as hot as the right one. Swapping the valves
indicates that the valve is not the problem.

Can anyone suggest a solution (other than using it as the world's heaviest
paperweight)?

I live in the North West of England. Is there anyone in the region who could
fix it?

Thanks for any help.

Steve