...and I can't see a way of getting into the thing to check the fuse
Don't bother -- there probably isn't a fuse inside of it anyway (maybe a fusable link?) and if you go
here you can find a very serviceable replacement for just $6.50. Of course shipping to U.K. will probably run you about twice that amount, so maybe for you it isn't such a good deal after all.
But for anybody looking for a few empeg-compatible power supplies, these work very well, the company is reliable and ships very quickly and is even good about answering email quesitons about their products.
tanstaafl.
"There Ain't No Such Thing As A Free Lunch"