Thanks Keith. Yes, the speaker itself wasn't working.
I've gone past the stage where I'm comfortable working on it, so it looks like it's off to a dealer. How long is a piece of string question: would you have any idea of repair costs (clearly dependant on what's failed I know, but do you know a dealer's labour rate?)
I see that Ian Kinsella is at Kings Street; I've had several conversations with him at Warrington, although I used to deal with Russ. I'll give them a call and see what's involved in getting it to them.
mobe, cheers for that, just hope I can get it repaired reasonably. The Merc's cost a fortune this year! :)