Pioneer dcs 313 left rear speaker clicks when volume raised

[mrplop]

This is really bugging the hell out of me - this problem just occured suddenly - whenever I turn up the volume on the remote you can hear a loud popping noise from the left rear speaker.
I've tried changing the speaker at the connection from the player and at the back of the speaker itself - the left rear still clicks.
I've also tried unplugging the whole thing and letting it cool down but it still the popping still happens when the volume is raised - any ideas anyone?

[Samlaren]

The amplifier for the left surround is not working correctly=time for service!

[mrplop]

Gosh thanks for that!
I think you'll be a valued member of this forum - no really I do...